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Friday, May 24, 2013
Endocrine Tests for Hypertension?
What endocrine tests should be done on a teenager with primary hypertension? Our son (whom I previously emailed Dr. Lam about - thank you for responding!) has hypertension and, despite a biopsy finding of Thin Basement Membrane, he has no hematuria and his nephrologist is inclined to still classify the hypertension as primary. His cardiologist asked if a "full endocrine workup" had been done - in your opinion, what would that entail? And what can/should be checked while a patient is also taking Enalapril? It`s quite probably that our nephrologist - whom we like and respect very much - has already covered all the bases, but I thought I`d ask here because I`m not sure what a "full endocrine workup" even is.
Whether or not a full endocrine workup needs to be done depends on other characteristics of your son and your family, such as:
1) severity of the hypertension: if it's easily controlled on enalapril, it's less likely to have an endocrine cause.
2) race: people of African origin are more likely to have a genetic (rather than endocrine) basis for hypertension.
3) family history: if hypertension runs in the family, it is less likely that he has a rare endocrine cause.
4) presence/absence of symptoms of a tumor called "pheochromocytoma," an endocrine tumor that periodically secretes hormones that result in attacks of hypertension, headache, heart-racing, and sweating. (If needed, this rare disorder can be screened for by 24-hr urine collections and blood tests, which are not affected by enalapril, and by imaging studies.)
5) presence/absence of obesity: even kids with obesity have a great likelihood of developing hypertension at a young age.
If 1), 2), 4), and 5) do not seem to apply to your son, it is possible that he indeed has "primary" or "essential" hypertension - especially if you do have a family history of hypertension.
In general, screening of young people with hypertension should focus on looking for:
1) kidney disease, as manifested by protein in the urine, abnormal BUN and/or creatinine (blood tests), or abnormalities of the kidneys on ultrasound exam.
2) coarctation of the aorta (a constriction in the aorta), which results in high BP in the arms but not the legs. If found, this disorder can be surgically repaired.
3) renovascular hypertension: a narrowing in one or both of the large arteries that supply the two kidneys; this can be diagnosed by an arteriogram (a radiologic study in which dye is introduced into the bloodstream, and a series of rapid pictures is taken of the kidneys as the dye flows through the arteries into the kidneys). If present, this disorder can be surgically repaired.
4) an adrenal tumor (either a pheochromocytoma, as described above, or a benign adrenal adenoma); an adrenal adenoma should be suspected if routine blood tests reveal a low potassium and high bicarbonate level.
Do not hesitate to ask your nephrologist about this: one thing that a nephrologist should be doing is to balance the probability of your son's actually having some rare disorder against the cost and difficulty of running a battery of tests that is unlikely to yield anything. As described above, not every patient needs a "full endocrine workup."
Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University