Allon M, Harrow A, Pasque C B, Rodriguez M
University of Oklahoma School of Medicine, Nephrology Section, Oklahoma City.
J Am Soc Nephrol. 1990 Aug;1(2):205-10. doi: 10.1681/ASN.V12205.
The mechanism responsible for renal tubular abnormalities in sodium and water excretion in hypothyroid patients is poorly understood. To evaluate the possible contribution of the reduced glomerular filtration rate of hypothyroidism to these abnormalities, tubular function in hypothyroid patients was compared with that in patients with chronic renal failure and in normal subjects. The lithium clearance method and oral water loading were used to evaluate parameters of tubular sodium and water handling, respectively. The hypothyroid and the chronic renal failure patients were selected to have similar reductions in glomerular filtration rate. As compared to the normal subjects, the hypothyroid and chronic renal failure patients had a decrease in proximal sodium reabsorption and an increase in distal sodium reabsorption. The changes in tubular handling of sodium were not different in the hypothyroid and the chronic renal failure patients. Maximal urinary flow rate and free water clearances were similarly reduced in the hypothyroid patients and the chronic renal failure patients. For all subjects studied, proximal sodium reabsorption and maximal urinary volume were directly correlated with the glomerular filtration rate, and distal nephron sodium reabsorption was proportionate to delivery of sodium from the proximal tubule. The results suggest that the abnormalities in tubular sodium and water handling in hypothyroid patients are comparable to those present in other patients with a similar degree of renal insufficiency. Thus, the tubular abnormalities in hypothyroidism may be a consequence of the associated decrease in glomerular filtration rate.
甲状腺功能减退患者肾小管钠和水排泄异常的机制目前尚不清楚。为了评估甲状腺功能减退导致的肾小球滤过率降低对这些异常的可能影响，将甲状腺功能减退患者的肾小管功能与慢性肾衰竭患者及正常受试者进行了比较。分别采用锂清除率法和口服水负荷试验来评估肾小管钠和水处理的参数。选择甲状腺功能减退患者和慢性肾衰竭患者使其肾小球滤过率有相似程度的降低。与正常受试者相比，甲状腺功能减退患者和慢性肾衰竭患者近端钠重吸收减少，远端钠重吸收增加。甲状腺功能减退患者和慢性肾衰竭患者肾小管对钠的处理变化并无差异。甲状腺功能减退患者和慢性肾衰竭患者的最大尿流率和自由水清除率同样降低。对于所有研究对象，近端钠重吸收和最大尿量与肾小球滤过率直接相关，远端肾单位钠重吸收与近端小管钠的输送成比例。结果表明，甲状腺功能减退患者肾小管钠和水处理异常与其他肾功能不全程度相似的患者相当。因此，甲状腺功能减退时的肾小管异常可能是肾小球滤过率相关降低的结果。
