COMPOSITION OF FLUID IN 12 CYSTS OF A POLYCYSTIC KIDNEY (REPRINTED FROM N ENGL J MED, VOL 281, PG 985, 1969)

Analyses of the chemical composition of fluid in 12 cysts of a polycys tic kidney disclosed marked variations in the concentrations of select ed cations, glucose, urea and creatinine, The concentrations of sodium ranged from 3.1 to 150.0 mEq per liter, of potassium from 4.6 to 58.1 mEq per liter, of hydrogen from 13 to 9800 nanoEq per liter and of cr eatinine from 11 to 87 mg per 100 ml. The concentrations of sodium var ied directly with those of calcium and inversely with those of potassi um, hydrogen, ammonium and magnesium, suggesting that the cyst walls w ere functioning as either proximal or distal nephrons, In cysts whose contents reflected distal tubular activity, amino acids contributed 50 to 100 mOsm per kilogram of water to the osmotic activity of the flui d.