Citation Nr: 1339020 Decision Date: 11/26/13 Archive Date: 12/06/13 DOCKET NO. 09-28 738 ) DATE ) ) On appeal from the Department of Veterans Affairs Regional Office in Denver, Colorado THE ISSUE Entitlement to service connection for hypertension, including as a result of herbicide exposure in service and as secondary to service-connected diabetes mellitus. REPRESENTATION Appellant represented by: Disabled American Veterans ATTORNEY FOR THE BOARD C. Ferguson, Counsel INTRODUCTION The Veteran, who is the appellant, had active service from July 1954 to March 1984. This matter comes before the Board of Veterans' Appeals (Board) on appeal from a July 2007 rating decision of the Department of Veterans Affairs (VA) Regional Office (RO) in Denver, Colorado. The Board has reviewed the Veteran's physical claims file, as well as the Veteran's electronic file on the "Virtual VA" system, to ensure a complete review of the evidence in this case. In March 2012, the Board denied the Veteran's claim for service connection for hypertension, and the Veteran appealed the decision to the U.S. Court of Appeals for Veterans' Claims (Court). In October 2012, the Court granted a Joint Motion for Remand (JMR) and ordered that the Board's March 2012 decision denying the Veteran's claim be vacated and remanded for readjudication. In February 2013, the Board again denied service connection for hypertension, and the Veteran appealed the decision to the Court. In August 2013, the Court granted a JMR and ordered that the Board's February 2013 decision denying the Veteran's claim be vacated and remanded for readjudication. The case has been returned to the Board following the Court Order. This appeal has been advanced on the Board's docket pursuant to 38 C.F.R. § 20.900(c) (2013). 38 U.S.C.A. § 7107(a)(2) (West 2002). FINDINGS OF FACT 1. The Veteran served in the Republic of Vietnam from November 1968 to November 1969, so is presumed to have been exposed to herbicides during service. 2. There was neither vascular injury or disease nor chronic symptoms of hypertension manifested during service. 3. Symptoms of hypertension have not been continuous since separation from service and did not manifest to a compensable degree in the year following separation from service. 4. The Veteran's current hypertension is not causally or etiologically related to service. 5. The Veteran's hypertension is not caused by, or increased in severity beyond the natural progress of the disease by, a service-connected disability. CONCLUSION OF LAW Hypertension was not incurred in active military service, may not be presumed to have been incurred in service, and was neither caused nor aggravated by a service-connected disability. 38 U.S.C.A. §§ 1110, 1112, 1113, 1116, 1131, 5103, 5103A (West 2002); 38 C.F.R. §§ 3.159, 3.303, 3.307, 3.309, 3.310 (2013). REASONS AND BASES FOR FINDINGS AND CONCLUSION Duties to Notify and Assist The Veterans Claims Assistance Act of 2000 (VCAA) enhanced VA's duty to notify and assist claimants in substantiating their claims for VA benefits. 38 U.S.C.A. §§ 5100, 5102, 5103, 5103A, 5107, 5126 (West 2002); 38 C.F.R. §§ 3.102, 3.156(a), 3.159, 3.326(a) (2013). Upon receipt of a complete or substantially complete application for benefits, VA is required to notify the claimant and his representative of any information, and any medical or lay evidence, that is necessary to substantiate the claim. 38 U.S.C.A. § 5103(a); 38 C.F.R. § 3.159(b). Proper notice from VA must inform the claimant of any information and evidence not of record (1) that is necessary to substantiate the claim; (2) that VA will seek to provide; and (3) that the claimant is expected to provide. 38 C.F.R. § 3.159(b)(1). This notice must be provided prior to an initial unfavorable decision on a claim by the RO. Mayfield v. Nicholson, 444 F.3d 1328 (Fed. Cir. 2006); Pelegrini v. Principi, 18 Vet. App. 112 (2004). The United States Court of Appeals for Veterans Claims (Court) issued a decision in the appeal of Dingess v. Nicholson, 19 Vet. App. 473 (2006), which held that the notice requirements of 38 U.S.C.A. § 5103(a) and 38 C.F.R. § 3.159(b) apply to all five elements of a service-connection claim, including the degree of disability and the effective date of an award. Those five elements include: (1) veteran status; (2) existence of a disability; (3) a connection between a veteran's service and the disability; (4) degree of disability; and (5) effective date of the disability. If complete notice is not provided until after the initial adjudication, such a timing error can be cured by subsequent legally adequate VCAA notice, followed by readjudication of the claim, as in a Statement of the Case (SOC) or Supplemental SOC (SSOC). Moreover, where there is an uncured timing defect in the notice, subsequent action by the RO which provides the claimant a meaningful opportunity to participate in the processing of the claim can prevent any such defect from being prejudicial. Mayfield v. Nicholson, 499 F.3d 1317, 1323-24 (Fed. Cir. 2007); Prickett v. Nicholson, 20 Vet. App. 370, 376 (2006). In this case, an August 2006 notice letter sent prior to the initial denial of the claim apprised the Veteran of the information and evidence necessary to substantiate the claim for service connection, which information and evidence that he was to provide, and which information and evidence that VA would attempt to obtain on his behalf. In this regard, the RO advised the Veteran of what the evidence must show to establish entitlement to service-connected compensation benefits for the claimed disability, and described the types of information and evidence that the Veteran needed to submit to substantiate the claim. The RO also explained what evidence VA would obtain and make reasonable efforts to obtain on the Veteran's behalf in support of the claim. The RO further informed the Veteran how VA determines the disability rating and effective date once service connection is established. An April 2007 notice letter sent after the initial denial of the claim advised the Veteran of the evidence needed to establish service connection for hypertension on a secondary basis, and the claim was subsequently readjudicated. In addition to the VCAA letter notice, the Veteran has been provided with a copy of the above rating decision and the SOC, which included a discussion of the facts of the claim, pertinent laws and regulations, notification of the bases of the decision, and a summary of the evidence considered. In view of the foregoing, the Board concludes that the requirements of the notice provisions of the VCAA have been met, and there is no outstanding duty to inform the Veteran that any additional information or evidence is needed. Regarding VA's duty to assist in claims development, the Board notes that the record contains all available evidence pertinent to the claim. VA has requested records identified throughout the claims process. The Veteran was given appropriate notice of the responsibility to provide VA with any treatment records pertinent to the claim, and the record contains sufficient evidence to make a decision on the claim. The service treatment records (STRs) are included in the claims file, and available post-service treatment records identified as relevant to the Veteran's claim have been obtained or otherwise submitted. There are no additional treatment records found in the Veteran's Virtual VA file. The Veteran also underwent a VA medical examination in connection with his claim in March 2007. The VA medical examiner was adequately informed of the Veteran's relevant medical history and symptomatology and provided a sound rationale for the medical opinion. For these reasons, the Board finds that the medical examination report is adequate and no further medical examination or medical opinion is needed. The Board is aware of the Court's often stated interest in conservation of judicial resources and in avoiding piecemeal litigation. See Harris v. Derwinski, 1 Vet. App. 180, 183 (1991) ("Court will [not] review BVA decisions in a piecemeal fashion"); Fugere v. Derwinski, 1 Vet. App. 103, 105 (1990) ("[a]dvancing different arguments at successive stages of the appellate process does not serve the interests of the parties or the Court"). In this case, neither the Veteran nor the representative has made the RO or the Board aware of any notice defect or any additional evidence relevant to the appeal that needs to be obtained. The Court-adopted Joint Motion did not identify any defect in the Board's February 2013 decision regarding the discussion of, or compliance with, the provisions of the VCAA. Rather, the reason for remand was indicated to be the Board's failure to properly justify its attribution of weight of the evidence submitted by the Veteran's private treating medical provider. Given the foregoing, the Board concludes that the Veteran has been provided with proper notice and all relevant facts have been properly and sufficiently developed in this appeal. No further notice or development is required. In view of the foregoing, the Board will proceed with appellate review. Legal Criteria for Service Connection It is the Board's responsibility to evaluate the entire record on appeal. See 38 U.S.C.A. § 7104(a) (West 2002). The Board has thoroughly reviewed all the evidence of record in this case. The analysis below focuses on the most salient and relevant evidence and on what this evidence shows, or fails to show, on the claim. When there is an approximate balance in the evidence regarding the merits of an issue material to the determination of the matter, the benefit of the doubt in resolving each such issue shall be given to the claimant. 38 U.S.C.A. § 5107(b) (West 2002); 38 C.F.R. § 3.102 (2013). In Gilbert v. Derwinski, 1 Vet. App. 49, 53 (1990), the U.S. Court of Appeals for Veterans Claims held that an appellant need only demonstrate that there is an "approximate balance of positive and negative evidence" in order to prevail. The Court has also stated, "It is clear that to deny a claim on its merits, the evidence must preponderate against the claim." Alemany v. Brown, 9 Vet. App. 518, 519 (1996), citing Gilbert. Service connection may be granted for a disability resulting from disease or injury incurred in or aggravated by active military, naval, or air service. 38 U.S.C.A. §§ 1110, 1131; 38 C.F.R. § 3.303(a). As a general matter, service connection for a disability requires competent evidence of (1) the existence of a current disability; (2) the existence of the disease or injury in service, and; (3) a relationship or nexus between the current disability and any injury or disease during service. Shedden v. Principi, 381 F.3d 1163 (Fed. Cir. 2004); see also Hickson v. West, 12 Vet. App. 247, 253 (1999), citing Caluza v. Brown, 7 Vet. App. 498, 506 (1995), aff'd, 78 F.3d 604 (Fed. Cir. 1996). The Veteran is currently diagnosed with hypertension. Hypertension is a "chronic disease" listed under 38 C.F.R. § 3.309(a); therefore, the presumptive service connection provisions under 38 C.F.R. § 3.303(b) for service connection based on "chronic" symptoms in service and "continuous" symptoms since service are applicable. Walker v. Shinseki, 708 F.3d 1331 (Fed. Cir. 2013). For the showing of chronic disease in service, there is required a combination of manifestations sufficient to identify the disease entity, and sufficient observation to establish chronicity at the time. With chronic disease as such in service, subsequent manifestations of the same chronic disease at any later date, however remote, are service-connected, unless clearly attributable to intercurrent causes. If a condition noted during service is not shown to be chronic, then generally, a showing of continuity of symptoms after service is required for service connection. 38 C.F.R. § 3.303(b). Service connection may also be granted for any disease diagnosed after discharge, when all the evidence, including that pertinent to service, establishes that the disease was incurred in service. 38 C.F.R. § 3.303(d). In addition, the law provides that, where a veteran served ninety days or more of active service, and certain chronic diseases such as hypertension become manifest to a degree of 10 percent or more within one year after the date of separation from such service, such disease shall be presumed to have been incurred in service, even though there is no evidence of such disease during the period of service. 38 U.S.C.A. §§ 1101, 1112, 1113, 1137 (West 2002); 38 C.F.R. §§ 3.307, 3.309(a). While the disease need not be diagnosed within the presumption period, it must be shown, by acceptable lay or medical evidence, that there were characteristic manifestations of the disease to the required degree during that time. Id. In order to establish presumptive service connection for a disease associated with exposure to certain herbicide agents, a veteran must show the following: (1) that he served in the Republic of Vietnam during the period beginning on January 9, 1962, and ending on May 7, 1975 (or was otherwise exposed to an herbicide agent during active service); (2) that he currently suffers from a disease associated with exposure to certain herbicide agents enumerated under 38 C.F.R. § 3.309(e); and (3) that the current disease process manifested to a degree of 10 percent or more within the specified time period prescribed in section 3.307(a)(6)(ii). 38 U.S.C.A. § 1116; 38 C.F.R. §§ 3.307(a)(6), 3.309(e). If a veteran was exposed to a herbicide agent during active military, naval, or air service, the certain diseases shall be service-connected, if the requirements of 38 C.F.R. § 3.307(a) are met, even if there is no record of such disease during service. During the pendency of this appeal, on August 31, 2010, the Secretary published a final rule in the Federal Register amending 38 C.F.R. § 3.309(e). See 75 Fed. Reg. 53,202. The final rule was effective August 31, 2010. Specifically, VA amended 38 C.F.R. § 3.309(e) to add hairy cell leukemia and other chronic B-cell leukemias, Parkinson's disease, and ischemic heart disease (including, but not limited to, acute, subacute, and old myocardial infarction; atherosclerotic cardiovascular disease including coronary artery disease (including coronary spasm) and coronary bypass surgery; and stable, unstable and Prinzmetal's angina) to the list of diseases associated with exposure to certain herbicide agents. A newly added Note 3 at the end of § 3.309 states that: "for purposes of this section, the term ischemic heart disease does not include hypertension or peripheral manifestations of arteriosclerosis such as peripheral vascular disease or stroke, or any other condition that does not qualify within the generally accepted medical definition of ischemic heart disease." Service connection may be granted for disability which is proximately due to, or aggravated by, a service-connected disease or injury. 38 C.F.R. § 3.310(a). "When aggravation of a veteran's non-service-connected condition is proximately due to or the result of a service-connected condition, such veteran shall be compensated for the degree of disability (but only that degree) over and above the degree of disability existing prior to the aggravation." Allen v. Brown, 7 Vet. App. 439 (1995). Competency of evidence differs from weight and credibility. Competency is a legal concept determining whether testimony may be heard and considered by the trier of fact, while credibility is a factual determination going to the probative value of the evidence to be made after the evidence has been admitted. Rucker v. Brown, 10 Vet. App. 67, 74 (1997); Layno v. Brown, 6 Vet. App. 465, 469 (1994); see also Cartright v. Derwinski, 2 Vet. App. 24, 25 (1991) ("although interest may affect the credibility of testimony, it does not affect competency to testify"). In rendering a decision on appeal, the Board must analyze the credibility and probative value of the evidence, account for the evidence which it finds to be persuasive or unpersuasive, and provide the reasons for its rejection of any material evidence favorable to the claimant. See Gabrielson v. Brown, 7 Vet. App. 36, 39-40 (1994); Gilbert, 1 Vet. App. at 57. A veteran is competent to describe symptoms that he or she experienced in service or at any time after service when the symptoms he or she perceived, that is, experienced, were directly through the senses. 38 C.F.R. § 3.159 (competent lay evidence means any evidence not requiring that the proponent have specialized education, training, or experience; lay evidence is competent if it is provided by a person who has knowledge of facts or circumstances and conveys matters that can be observed and described by a lay person.); Layno, 6 Vet. App. at 469-71 (lay testimony is competent as to symptoms of an injury or illness, which are within the realm of one's personal knowledge; personal knowledge is that which comes to the witness through the use of the senses; lay testimony is competent only so long as it is within the knowledge and personal observations of the witness, but lay testimony is not competent to prove a particular injury or illness); see Barr v. Nicholson, 21 Vet. App. 303 (2007) (lay testimony is competent to establish the presence of observable symptomatology, where the determination is not medical in nature and is capable of lay observation). Lay evidence may establish a diagnosis of a simple medical condition, a contemporaneous medical diagnosis, or symptoms that later support a diagnosis by a medical professional. Jandreau, 492 F. 3d at 1377. Also, a veteran as a layman is competent to offer an opinion on a simple medical condition. Davidson v. Shinseki, 581 F. 3d 1313, 1316 (Fed. Cir. 2009) (citing Jandreau). VA must consider the competency of the lay evidence and cannot outright reject such evidence on the basis that such evidence can never establish a medical diagnosis or nexus; however, this does not mean that lay evidence is necessarily always sufficient to identify a medical diagnosis, but rather only that it is sufficient in those cases where the layman is competent and does not otherwise require specialized medical training and expertise to do so, i.e., the Board must determine whether the claimed disability is a type of disability for which a layperson is competent to provide etiology or nexus evidence. See Davidson, 581 F. 3d at 1316 (recognizing that, under 38 U.S.C.A. § 1154(a), lay evidence can be competent and sufficient to establish a diagnosis of a condition when a layman is competent to identify the medical condition; he is reporting a contemporaneous medical diagnosis; or lay testimony describing symptoms at the time supports a later diagnosis by a medical professional). Service Connection for Hypertension In this case, the Veteran's primary contention is that he has developed hypertension as a result of his service-connected diabetes mellitus. Before addressing this contention, it is incumbent on the Board to explore all possible theories by which service connection may be established, including the Veteran's contention that the hypertension is itself the result of defoliant exposure in service. It is initially noted that the record shows that the Veteran served in the Republic of Vietnam from November 1968 to November 1969 and is presumed to have been exposed to herbicide agents. "Hypertension" refers to persistently high arterial blood pressure. Medical authorities have suggested various thresholds ranging from 140 mm Hg systolic and from 90 mm Hg diastolic to as high as 200 mm Hg systolic and 110 mm Hg diastolic as reflective of hypertension. Dorland's Illustrated Medical Dictionary 909 (31st ed. 2007). Similarly, for VA rating purposes, the term hypertension means that the diastolic blood pressure is predominantly 90 mm or greater. The term "isolated systolic hypertension" means that the systolic blood pressure is predominantly 160 mm or greater with a diastolic blood pressure of less than 90 mm. See 38 C.F.R. § 4.104, Diagnostic Code 7101, Note 1 (2013). After a review of all the evidence, both lay and medical, the Board finds that no vascular injury, disease, or chronic symptoms of hypertension occurred during service or were manifested during service. Review of the Veteran's STRs shows that, while he was on active duty, his blood pressure readings were consistently within normal limits, to include at the December 1983 service retirement examination (i.e., 110/76). Also, on the December 1983 service retirement report of medical history, the Veteran checked "No" when asked if he then had or ever had had high or low blood pressure. Additionally, on medical examination performed by VA in July 1984 (i.e., approximately four months after service retirement), the Veteran's blood pressure reading was 115/82. Thus, blood pressure readings throughout service and shortly after service retirement are within normal limits and the Veteran does not contend that symptoms of hypertension began in service; therefore, the evidence does not in any way indicate the presence of hypertension or chronic symptoms of hypertension during service. As the weight of the evidence demonstrates no "chronic" symptoms of hypertension during service, the criteria for presumptive service connection under 38 C.F.R. § 3.303(b) based on "chronic" symptoms in service are not met. The Board next finds that the evidence shows that the Veteran did not continuously manifest symptoms of hypertension since service, including not to a degree of ten percent within one year of service retirement. See 38 C.F.R. § 4.104, Diagnostic Code 7101. Review of the Veteran's post-service treatment records, including records from a private medical provider, as well as VA medical examination reports dated in 1984 and 1985, show that the Veteran's blood pressure readings were within normal limits for many years following service. Although the earliest diagnosis reflected in treatment records currently of record is dated in 2000, a September 2005 letter from a VA environmental physician to the Veteran regarding the results of his Agent Orange medical examination reveals that the Veteran reportedly then had high blood pressure, which had been diagnosed in 1997. The Veteran is competent to report a past medical diagnosis of hypertension and there is no indication that his account is not credible. The absence of post-service findings, diagnosis, or treatment for hypertension until 1997 (i.e., approximately thirteen years after service retirement) is one factor that tends to weigh against a finding of hypertension in service or continuous symptoms after service separation. See Buchanan v. Nicholson, 451 F.3d 1336 (Fed. Cir. 2006) (the lack of contemporaneous medical records is one fact the Board can consider and weigh against the other evidence, although the lack of such medical records does not, in and of itself, render the lay evidence not credible); see also Maxson v. Gober, 230 F.3d 1330, 1333 (Fed. Cir. 2000) (the passage of many years between discharge from active service and the medical documentation of a claimed disability is one factor to consider as evidence against a claim of service connection). As the weight of the evidence demonstrates no "continuous" symptoms of hypertension since service, the criteria under 38 C.F.R. § 3.303(b) for presumptive service connection for "continuous" post-service symptoms are not met. Moreover, the Veteran does not contend that his hypertension manifested to a compensable degree during the first post-service year. Additionally, as stated above, the evidence does not otherwise show manifestations of hypertension to a degree of ten percent within one year of service separation. Therefore, the Board finds that, because hypertension was not manifested to a degree of ten percent within one year of service separation, there is no basis for presumptive service connection. 38 C.F.R. §§ 3.307, 3.309. The Board further finds that the weight of the evidence demonstrates that hypertension, which first manifested many years after service, was not caused by any in-service event, including defoliant exposure during service. As noted, hypertension is, by regulation, not a disease for which service connection may be presumed as being the result of herbicide exposure. The scientific studies reviewed as part of that regulatory process established no correlation between herbicide exposure and hypertension that developed many years later such that hypertension was specifically excluded by regulation as a disease associated with herbicide exposure. There is no competent medical evidence of record that has even suggested a relationship between the current hypertension and active military service, to include in-service exposure to herbicide agents or defoliants. As found above, the record further does not show hypertension in service, or even symptoms of hypertension in service, or continuous symptoms of hypertension since service. As such there is no factual basis for the need for the Board to seek an additional nexus opinion, or upon which a medical professional could relate the Veteran's hypertension to service, as any purported direct nexus opinion would be based a factually inaccurate assumption of chronic or continuous symptoms or would be inconsistent with the scientific studies establishing the lack of such relationship. As such, direct and presumptive service connection for hypertension may not be established, including as due to herbicide exposure. 38 C.F.R. §§ 3.303, 3.307, 3.309. The Board further finds that the weight of the evidence demonstrates that hypertension is not caused by, or aggravated by, the service-connected disability of diabetes mellitus. This is the Veteran's primary contention on appeal - i.e., that his hypertension is related to diabetes mellitus for which service connection has been established, effective in August 2006. The Board notes that the possibility of a relationship between hypertension and diabetes on the basis of causation or aggravation was specifically considered and rejected in a March 2007 VA medical examination report. At that time, the diagnoses were diabetes mellitus, type II, and hypertension, onset antedating the appearance of diabetes without evidence of left ventricular hypertrophy. The examining VA physician wrote that it was the consensus of the medical staff that, in the absence of proteinuria, hypertension was neither due to, nor aggravated by, diabetes mellitus. The examining VA physician has medical expertise (more extensive than the medical training of a physician's assistant), had adequate information on which to base his medical opinion, and provided adequate rationale for the conclusion based on medical principles. For these reasons, the March 2007 VA medical opinion is of great probative weight. The Board has considered the May 2007 letter submitted by the Veteran's private medical provider (P.E.S., P.A.-C.). In the May 2007 statement, the physician's assistant wrote that the Veteran had been a patient of the practice for "quite a few years." The physician's assistant stated that the Veteran's elevated blood pressure was first noticed in September 2000, which was initially managed with lifestyle, exercise, and diet, but years later required medication due to a more sustained elevation of blood pressure. The physician's assistant then wrote that the Veteran was started on diabetic medication in June 2004 and, due to the diabetes, there was a need to lower his blood pressure "even lower than what it was." He further stated that the Veteran was started on blood pressure medication in December 2004 in order to treat his blood pressure as well as to help preserve kidney function due to diabetes. In reviewing the May 2007 statement, the Board initially notes that the private medical provider indicates that the diagnosis of hypertension and symptoms related thereto pre-dated the diagnosis and symptoms of diabetes, which is consistent with the March 2007 VA medical opinion's factual assumption that hypertension existed prior to the onset of diabetes. Although the Veteran reported at the March 2007 VA medical examination that he was diagnosed with hypertension in 2004, the statement is inconsistent with, and outweighed by, other more credible evidence, to include his own prior statements. For example, the treatment records from the physician's assistant reflect a diagnosis of mild hypertension in 2000. Because treatment records are likely to reflect accurately both the medical history and current medical conditions, they are particularly credible and of significant probative value. Also, approximately one year before filing the current service connection claim for hypertension, the Veteran told the physician who performed the September 2005 Agent Orange examination that hypertension was diagnosed as early as 1997 (and diabetes had been diagnosed during the early part of 2005). Thus, the statement at the March 2007 VA medical examination that hypertension was first diagnosed in 2004 is inconsistent with the treatment records and the Veteran's prior statement made approximately one year before filing the claim for service connection; therefore, it is not deemed credible and is of no probative value. The fact that diabetes was diagnosed in 2004 or 2005 (i.e., several years after the hypertension diagnosis) is not in dispute. Symptoms of diabetes are not shown to have manifested prior to 2004; thus, because both symptoms and diagnosis of hypertension existed prior to symptoms and diagnosis of diabetes, this chronological factor weighs heavily against finding that service-connected diabetes mellitus caused hypertension. Additionally, in the May 2007 statement, the physician's assistant noted that the Veteran began blood pressure medication shortly after being diagnosed with diabetes in an effort to lower his blood pressure even further, which does not in any way indicate that there had been an increase in severity of hypertension symptomatology due to diabetes. Rather, the statement of the physician's assistant merely suggests that the decision to place the Veteran on blood pressure medication was made to better manage the hypertension in light of the recent diabetes diagnosis so that the kidney function may be preserved. The reasonable inference is only that the hypertension could be a factor that may worsen the kidney function. The statement only has a tendency to suggest that hypertension and/or service-connected diabetes mellitus, if left untreated or uncontrolled, may potentially impair kidney function. The physician's assistant's statement does not in fact constitute an opinion on whether there had been an aggravation of the Veteran's hypertension by service-connected diabetes, and no such logical inference is available from this statement; therefore, the May 2007 statement is of no probative value in addressing the medical question of whether service-connected diabetes permanently worsened hypertension beyond the natural progression of the disease. Furthermore, the same physician's assistant later provided a statement dated in June 2008 wherein he summarized the Veteran's medical history, to include treatment for hypertension and diabetes mellitus, and concluded that the Veteran's new complaints of burning in his feet and leg were indicative of peripheral neuropathy "more than likely" secondary to his diabetes. The physician's assistant did not provide a medical opinion on whether hypertension was secondary to diabetes mellitus; therefore, the June 2008 statement is of no probative value in addressing the medical question of whether diabetes caused hypertension or permanently worsened hypertension beyond the natural progression of the disease. Although the Veteran has asserted his belief that his diabetes mellitus caused or aggravated his hypertension (see November 2008 statement wherein he wrote that his "blood pressure rose along with [his] diabetic situation"), he is a lay person and does not have the requisite medical expertise to render a competent medical opinion regarding the relationship between the complex cardiovascular and endocrine system diagnoses of hypertension and diabetes mellitus on a causal or aggravation basis. Such diagnoses and opinions as to relationship involve an understanding of complex interactions between body systems (cardiovascular and endocrine), involve making findings based on medical knowledge and clinical testing results, and involve unseen systems processes and disease processes that are not observable by the five senses of a lay person. In addition, while a medical opinion considers symptoms to help determine the dates of onset of disabilities of hypertension and diabetes, the opinion is not based primarily on the reported symptoms that are capable of lay observation. Consequently, the Veteran's purported opinion relating diabetes to his service-connected hypertension is of no probative value. The theory of secondary service connection turns on the question of whether there exists a secondary medical relationship between current hypertension and service-connected diabetes mellitus. Questions of medical diagnosis and causation are within the province of medical professionals. Jones v. Brown, 7 Vet. App. 134, 137-38 (1994). In this case, the chronological fact of onset of symptoms and diagnosis of hypertension years before symptoms and diagnosis of diabetes mellitus weighs against a finding that the service-connected diabetes mellitus caused or aggravated the hypertension. The only probative medical opinion of record that directly addresses the likelihood of a secondary relationship between hypertension and diabetes mellitus is to the effect that, given the circumstances of this case, there is no secondary relationship between hypertension and diabetes mellitus on either a causation or aggravation basis. Also, as discussed above, no vascular injury, vascular disease, or chronic symptoms of hypertension manifested in service; no symptoms of hypertension continuously manifested since service; hypertension was not manifested to a compensable degree within a year of service; and no nexus relationship between the Veteran's hypertension and service, to include presumed Agent Orange exposure, is shown. In consideration thereof, the Board finds that the preponderance of the evidence is against the claim, and it must be denied. ORDER Service connection for hypertension, including as a result of herbicide exposure in service and as secondary to service-connected diabetes mellitus, is denied. ____________________________________________ J. PARKER Veterans Law Judge, Board of Veterans' Appeals Department of Veterans Affairs