Inappropriate Antidiuretic Hormone Secretion and Myxedema

Thyroid Hormone and the Kidney

“…due to retention of water in excess o f sodium. This hypothesis is supported by observations that hyponatremia is improved by water re striction [61,131], and that its correction following thyroid hormone therapy is accompanied initially by excretion of dilute urine so that the negative water balance exceeds the negative sodium balance [29,132].…”

“…In the more severe cases, concen trations can be strikingly decreased to levels as low as 100-110 mEq/1 [33,110,131], which contribute to the characteristic obtundation in myxedema. Since these patients have high radiosodium spaces [4], the hyponatremia is probably dilutional, i.e.…”

Symptomatic Hyponatremia in Association with a Low-Iodine Diet and Levothyroxine Withdrawal Prior to I131in Patients with Metastatic Thyroid Carcinoma

“…In our patients, although the duration of hypothyroidism was relatively short, the induction of hypothyroidism along with the low sodium intake, advanced age, and pulmonary and cerebral metastases may be responsible for causing hyponatremia. Earlier studies suggested that these may be related to AVP-dependent mechanisms (16)(17)(18), but AVP-independent mechanisms could also contribute (19)(20)(21)(22). Although enhanced renal sensitivity to AVP may contribute, in thyroid hormone deficiency renal tubular sensitivity to AVP is reduced (23,24).…”

Effect of TRH on Plasma Arginine Vasopressin

“…Hypothyroid subjects may also present with signs and symptoms of hyponatremia [4, 14, 17, 19, 21] and the syndrome of inap propriate antidiuretic hormone secretion [7,26] and may respond abnormally to oral wa terload [2,5], Reasons for the abnormal wa ter metabolism in this disease are not clear. Various hypotheses were advanced which implicate both renal and extrarenal factors.…”