Thiosulphate clearance in pregnancy.

In 1946, Gilman, Philips, and Koelle (1) reported observations on the renal clearance of thiosulphate in dogs. In 13 experiments, comprising 46 clearance periods, they found that the creatinine/thiosulphate clearance ratio fell within the range of 0.9 to 1.1. They concluded that thiosulphate is unique among inorganic ions in that it is neither reabsorbed nor excreted by the renal tubules when present in the glomerular filtrate in the concentration range of 13.3 to 66.6 mg. per 100 cc. Newman, Gilman, and Philips (2) subsequently reported a series of simultaneous inulin and thiosulphate clearances in man. Using the single injection method, they found that the thiosulphate/ inulin clearance ratio fell within the range of 0.7 to 1.3 (average 0.99 + 0.08) and that this ratio was independent of the plasma concentration between 6 and 60 mg. per 100 cc. The apparent identity of these clearances has been confirmed by Brun (3), Crawford (4), and Blegen, Qrning, and Aas (5), while Bj0rnboe, Dalgaard-Mikkelsen, and Raaschou (6) report that in three subjects the thiosulphate/inulin clearance ratio is higher when the urine is alkaline than when it is acid. More recently, Pitts and Lotspeich (7), employing thiosulphate to measure the filtration rate in dogs in connection with studies of acid-base balance, confirmed the identity of the thiosulphate/ creatinine clearance ratio (average 1.00, range 0.90 to 1.13) in this species, and stated that the administration of thiosulphate did not disturb either glomerular filtration or renal plasma flow. Since it appeared from this evidence that the thiosulphate clearance is a reliable measure of glomerular filtration rate, and since inulin was not obtainable in post-war Europe, a study of renal function in normal and toxemic pregnancy was