Comparative aspects of iodine conservation in mammals

1. Comparative aspects of iodine conservation in mammals were studied on the basis of published data on kidney and thyroid weights and function. 2. Very small mammals possessed an efficient reabsorption of iodide to compensate for the high glomerular filtration rate (GFR). 3. Humans and mammals of a similar and larger size had "lost" the ability to reabsorb iodide efficiently. 4. Very large mammals are protected against renal loss of iodide due to the relatively low GFR. 5. Thyroid weights in relation to body weight were highest in humans suggesting that humans and other mammals of a similar size are especially susceptible to iodine deficiency.