Thyroid hormone metabolism and thyroid diseases in chronic renal failure

Abstract

Patients with ESRD have multiple alterations of thyroid hormone metabolism in the absence of concurrent thyroid disease. These may include elevated basal TSH values, which may transiently increase to greater than 10 mU/liter, blunted TSH response to TRH, diminished or absent TSH diurnal rhythm, altered TSH glycosylation, and impaired TSH and TRH clearance rates. In addition, serum total and free T3 and T4 values may be reduced, free rT3 levels are elevated while total values are normal, serum binding protein concentrations may be altered, and disease-specific inhibitors reduce serum T4 binding. Changes in T4 and T3 transfer, distribution, and metabolism resemble those of other nonthyroidal illnesses, while changes in rT3 metabolism are disease specific. Dialysis therapy minimally affects thyroid hormone metabolism, while zinc and erythropoietin administration may partially reverse thyroid hormone abnormalities. Thyroid hormone metabolism normalizes with renal transplantation; however, glucocorticoid therapy may induce additional changes. ESRD patients may have an increased frequency of goiter, thyroid nodules, thyroid carcinoma, and hypothyroidism. Goiter and hypothyroidism may be induced by iodide excess, due to reduced renal iodide excretion, and may be reversed with iodide restriction in some patients. The increased frequency of thyroid nodules and malignancies in ESRD may relate to secondary hyperparathyroidism. After renal transplantation, the higher frequency of thyroid malignancies may relate to the immunosuppressed state. Clinical symptoms and signs and biochemical features of hypothyroidism and hyperthyroidism may be altered by concurrent ESRD. ESRD patients with hyperthyroidism or follicular neoplasms require reduced dosages of Na 131-I depending upon type, frequency, and duration of dialysis therapy.

Prevalence and Clinical Characteristics of Hypothyroidism in a Population Undergoing Maintenance Hemodialysis

“…Due to reduced deiodinase activity, tissue and circulating levels of the active form of T3 are low in kidney failure [14]. Because of reduced renal excretion, inorganic iodide generated by residual deiodinase activity accumulates in stage 4 and 5 CKD, which in turn dampens thyroid hormone synthesis.…”

“…Elevation of serum iodine levels result in prolongation of the Wolff-Chaikoff effect [21]. Iodine excess has been linked to increased prevalence of goiter and hypothyroidism reported in CKD [14,22]. A high exposure to iodine facilitates the development of hypothyroidism in CKD patients [23].…”

Thyroid Functional Status in Chronic Kidney Disease

“…In general, reduced T3 levels in ESRD patients are due to the decreased peripheral tissue conversion of T4 into T3, while thyroid gland production of T3 is normal and T3 clearance rates are normal or decreased, as in other non-thyroidal illnesses (4). Most patients with end-stage renal disease have decreased plasma levels of free triiodothyronine (FT3), which reflect diminished conversion of thyroxine (T4) to T3 in the periphery (5).…”

Kidney failure in the elderly due to hypothyroidism: a case report

“…This leads to deficits of renal function, associated with reductions in the cardiac output. 10,11 It can also cause glomerulopathy (nephritic and/ or nephrotic syndrome) and occur in diverse forms of chronic kidney disease, including in hemodialysis patients, thereby worsen ing the prognosis. 10 Most kidney abnormalities (structural, metabolic and morphological) caused by hypothyroidism can be reverted after supplementation with thyroxin.…”

“…10,11 It can also cause glomerulopathy (nephritic and/ or nephrotic syndrome) and occur in diverse forms of chronic kidney disease, including in hemodialysis patients, thereby worsen ing the prognosis. 10 Most kidney abnormalities (structural, metabolic and morphological) caused by hypothyroidism can be reverted after supplementation with thyroxin. 11 Here, we describe the case of a patient attended at the geriatric outpatient clinic of Hospital do Servidor Público Estadual, in São Paulo, who was diagnosed as presenting renal dysfunction associated with hypothyroidism.…”