Initial Laboratory Testing as per JNC 7

Initial Laboratory Testing Form

You have made the new diagnoses of Stage 1 Essential Hypertension in your patient Mary Johnson. The JNC 8 guidelines in 2013 do not discuss diagnosis and laboratory work up of hypertension. What initial laboratory testing would you order in the office as per JNC 7 standards regarding essential hypertension?(Choose all that apply)

1)Proper Element

Rate and rhythm issues – Is the patient bradycardic, tachycardic, or have an underlying heart block? Are beta blockers or calcium channel blockers contraindicated? Is there the possibility of undiagnosed hyperthyroidism? Are there rhythm disturbances such as atrial fibrillation?

Ischemia – Does the patient have evidence of ischemic disease or previously undiagnosed myocardial infarctions? Is there presence of end organ damage?

Hypertrophy – Does the patient have EKG signs of cardiac hypertrophy? Does the patient have left ventricular hypertrophy (LVH)? LVH is the second best prognosticator of death in all people. LVH is reversible with proper attention and medical management. The first and best prognosticator of death in all people is age (the older you are, the more likely you will die).

2) Not a Proper Element — TFTs – are not generally indicated in initial evaluation of essential hypertension patients unless you have clinical suspicion of hyperthyroidism or hypertension control can not be achieved.

3) Proper Element

Proteinuria – May be evidence of hypertensive nephropathy (target organ damage).

Glucosuria – May be evidence of undiagnosed diabetes or poorly controlled diabetes (co-morbidity and sign of metabolic syndrome).

4) Not a Proper Element — Echocardiograms – are not generally indicated in initial evaluation of essential hypertension patients unless you have clinical suspicion of congestive heart failure, valvular disease, or cardiomyopathy.

5) Proper Element — Elevated blood glucose – elevated random or fasting blood glucose may be evidence of undiagnosed diabetes or poorly controlled diabetes (co-morbidity and sign of metabolic syndrome). This could possibly affect the choice of first line agent to be used in managing hypertension.

6) Proper Element — Low hematocrit – Underlying anemic states in hypertensive patients make the likelihood of a major cardiovascular event more likely (strokes, heart attacks). If a hypertensive patient is found to be anemic, the underlying cause (example – colon cancer, uterine fibroids) must be found and addressed, and the anemia corrected. Anemia may also be the product of target organ damage in regards to severe end stage renal disease. A serum hemoglobin can also be used.

7) Not a Proper — Element Renal artery sonography – is not generally indicated in initial evaluation of essential hypertension patients unless you have clinical suspicion of renal artery stenosis or hypertension control cannot be achieved.

8) Proper Element — Several blood pressure medications can cause potassium derangements (ACE inhibitors, ARBs, and Potassium Sparing Diuretics causing or exacerbating hyperkalemia). A baseline potassium level is necessary. Furthermore, potassium disturbances can occur in Cushing’s syndrome or primary hyperaldosteronism.

9) Proper Element Elevated serum creatinine – This may be indicative of end organ damage (hypertensive nephropathy) from long term uncontrolled hypertension. Some blood pressure medications also elevate creatinine such as ACE inhibitors, ARBs, and diuretics.

10) Proper Element — One-third of patients with hyperparathyroidism and hypertension can be attributed to renal parenchymal damage due to nephrolithiasis. Increased calcium levels can also have a direct vasoconstrictive effect. It is unclear as to why the increased serum calcium level in hyperparathyroidism raises blood pressure, while epidemiologic studies suggest that a high calcium intake lowers blood pressure. It is also not clear as to why calcium channel blocker agents are effective antihypertensive agents.

11)Not a Proper Element — Serum chloride – is not generally indicated in initial evaluation of essential hypertension patients. There are no derangements of serum chloride due to hypertension or hypertensive medications. This test may often be bundled with other electrolyte serology that is recommended such as potassium, creatinine, glucose, or calcium (Chemistry 7, Chemistry 8, “SMAC”, electrolyte panel, etc.).

12) Not a Proper Element — Serum cortisol – is not generally indicated in initial evaluation of essential hypertension patients unless you have some clinical suspicion of Cushing’s disease or another metabolic disorder (causes of secondary hypertension) or hypertension control cannot be achieved.

13) Not a Proper Element — Random serum total cholesterol – is not cost effective in the initial evaluation of essential hypertension. A full lipid profile, after 9- to 12-hour fast, that includes high-density and low-density lipoprotein cholesterol, and triglycerides is important and cost effective. Hypertensive patients require the entire fasting cholesterol panel in order to properly assess lipid co-morbidities as part of metabolic syndrome and the risk of arteriosclerosis. These patients have fasting lipid panels as surveillance of cholesterol problems, and not as a general screening tool.

14) Proper Element — Lipid profile, after 9- to 12-hour fast, that includes high-density and low-density lipoprotein cholesterol, and triglycerides is important. Hypertensive patients require the entire fasting cholesterol panel in order to properly assess lipid co-morbidities as part of metabolic syndrome and the risk of arteriosclerosis. These patients have fasting lipid panels as surveillance of cholesterol problems, and not as a general screening tool.

15) Not a Proper Element — Abdominal MRI – is not generally indicated in initial evaluation of essential hypertension patients unless you have clinical suspicion of an aortic aneurysm.

16)Proper Element — The JNC 7 considers the measurement of urinary albumin excretion or albumin/creatinine ratio(ACR) optional except for those with diabetes or kidney disease where annual measurements should be made. This may become a recommended test for all hypertensive patients in future JNC reports because microalbuminuria does appear to have some prognostic implications.

17) Not a Proper Element– CBC – although a serum hemoglobin is recommended in the initial evaluation of essential hypertension, the white blood cell count and platelets are not generally indicated. A blood hematocrit can also be used.

18) Not a Proper Element — LFTs – are not generally indicated in initial evaluation of essential hypertension patients.

19)Not a Proper Element — Chest X-rays – are not generally indicated in initial evaluation of essential hypertension patients unless you have clinical suspicion of congestive heart failure or cardiomegaly.

20) Not a Proper Element — Serum sodium – is not generally indicated in initial evaluation of essential hypertension patients as per JNC 7. This is surprising considering that some patients, particularly the elderly, have been known to have serum sodium derangements from blood pressure medications (example – hyponatremia from diuretics and ACE inhibitors). This test may often be bundled with other electrolyte serology that is recommended such as potassium, creatinine, glucose, or calcium (Chemistry 7, Chemistry 8, “SMAC”, electrolyte panel, etc.).

Now review your responses above. All elements are tagged as Proper Element or Not a Proper Element.

More extensive testing for identifiable causes (secondary hypertension) is not generally indicated unless blood pressure control is not achieved.

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Initial Laboratory Testing as per JNC 7