Secondary focal segmental glomerulosclerosis in non-obese patients with increased muscle mass.
BACKGROUND
Secondary focal segmental glomerulosclerosis (FSGS) is a pattern of glomerular injury mediated by hyperfiltration and other adaptive structural-functional responses. We describe 3 non-obese patients with elevated body mass index (BMI) owing to increased muscle mass who had renal biopsy findings favoring a form of secondary FSGS.


METHODS
Clinical and pathologic data were obtained on 3 patients with 1) renal biopsy findings of focal segmental and/or global glomerulosclerosis with glomerulomegaly; 2) BMI > or = 30; 3) body fat percentage < 20%; 4) "highly muscular" appearance, and 5) proteinuria > or = 1 g/d without nephrotic syndrome. 24-hour urine creatinine excretion was used to estimate lean body mass and percentage body fat.


RESULTS
The 3 patients were males (age 38 - 48 years) employed in jobs requiring strenuous physical activity. BMIs ranged from 30.4 - 32.1 kg/m2 with body fat percentages of 12.9 - 16.8%. Creatinine clearances at time of biopsy ranged from 113 - 208 ml/min. Renal biopsies showed focal segmental and/or global glomerulosclerosis affecting a minority of glomeruli with glomerular hypertrophy and minimal (mean 15%) foot process effacement. Treatments included angiotensin-converting enzyme inhibitor, angiotensin II receptor blocker, or weight loss. Over a mean follow-up time of 24.3 months, serum creatinine remained stable and proteinuria decreased in all patients.


CONCLUSIONS
Non-obese patients with increased BMI due to elevated muscle mass are at risk of developing a secondary form of FSGS that resembles obesity-related glomerulopathy.
Schwimmer
J A
JA
Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
Markowitz
G S
GS
Valeri
A M
AM
Imbriano
L J
LJ
Alvis
R
R
D'Agati
V D
VD
D000328:Adult; D001824:Body Constitution; D015992:Body Mass Index; D005923:Glomerulosclerosis, Focal Segmental / Q000209:etiology* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*