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Thursday, April 17, 2014
TBM in Teenager
A recent renal biopsy on my son (16) found Thin Basement Membrane. He has had orthostatic proteinuria (on and off) for the past 6 years but then developed hypertension last year (now under control with Enalapril Maleate). The puzzling thing is that he`s never had hematuria and still does not have any. Also, there is no kidney disease in the family (but there is plenty of hypertension). Despite TBM being typically benign, we are concerned about his long-term prognosis. Can the hypertension be controlled indefinitely in a 16-yr. old? Is he at great risk for developing renal insufficiency?
You are right: TBM disease typically does not cause hypertension but typically does cause microscopic hematuria. Without seeing the renal biopsy or knowing your son's actual blood pressures or the exact results of his tests, it is hard to say what's going on, but here are some thoughts that may help:
1) He may have two unrelated conditions: orthostatic proteinuria (which is not rare in young people, does not cause any harm, and usually goes away on its own) and familial hypertension.
2) Since it must be extremely rare (if not unheard of) for a person with TBM disease NOT to have hematuria, I would question the reading of the kidney biopsy -- it may be worthwhile obtaining a second opinion by having a second pathologist look at the actual slides. However, also be aware that "sampling error" in the biopsy may lead to a mistaken diagnosis if diseased parts of the kidney are not included in the biopsy.
3) In any case, the hypertension is of concern in such a young person. Although his blood pressure may be able to be controlled indefinitely, good control is going to depend very much on your son's ability and willingness to take his med(s) regularly for the rest of his life. It will be very important for him to be closely followed by a good pediatrician (and later, a good internist) and to be seen occasionally by a nephrologist, in order to monitor his blood pressure control as well as to keep a close eye out for any signs of damage to the kidneys from the hypertension.
His likelihood of developing renal disease may also be determined not just by his blood pressure control, but by genetics. With all the hypertensive people in your family, it is good that no one has developed renal failure -- since a family history of hypertension-induced kidney failure certainly increases the risk in other members of the family.
Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University