Hemodialysis Patients with Incidental Hypothyroidism -The Approach to L-thyroxine

Abstract

The use of EPO in most HD patients to correct renal anemia [8,9] may also mask the similar symptoms and signs between hypothyroidism and uremia (i.e., anemia, lethargy, constipation, cold intolerance, and poor appetite) [10,11], thus making diagnosis of hypothyroidism difficult. Furthermore, the association of EPO with L-thyroxine therapy remains largely unknown [11][12][13][14]. Attempts to normalize circulating thyroid hormone for the EPO response may be harmful to HD patients with hypothyroidism, who may suffer excessive waste of protein nitrogen [1,2]. With hypothyroidism left untreated, the dosage of EPO can be increased to overcome the EPO resistance in HD patients. AbstractAim: This study investigated the effect of L-thyroxine on clinical manifestations and EPO responses, and the approach to L-thyroxine dosage adjustment for HD patients with Incidental hypothyroidism.Methods: Ten cases of Incidental hypothyroidism were diagnosed in 695 HD patients. In this study, L-thyroxine therapy was given only to hypothyroid HD patients with clinical symptoms, hematocrit <35%, and whose hypothyroidism was caused by medications which could not be discontinued. The initial dosage of L-thyroxine was 0.025 mg daily, and continuous adjustment was made according to clinical manifestations, patient's tolerance of L-thyroxine, and hematocrit level rather than TSH, T4 or FT4 value. Results:Of the 10 cases of Incidental hypothyroidism, 2 were autoimmune-induced, 5 were non-autoimmuneinduced, 2 were amiodarone-induced, and 1 was interferon-induced. Among them, 7 were treated with L-thyroxine and 3 were not. After L-thyroxine therapy, all 7 patients got symptoms improvement with 3 having EPO dosage reduced by more than 20%, 3 having hematocrit increased by more than 20%, and no patient requiring blood transfusion to keep hematocrit >30%. The clinical manifestations were found to improve after discontinuation of medications in two of those three patients with medication-induced hypothyroidism. L-thyroxine therapy may not be required for HD patients with hypothyroidism and hematocrit >35%.Conclusions: Adjustment of L-thyroxine dosage according to clinical manifestations, rather than TSH, T4 or FT4 value, is a practical and effective treatment approach for HD patients with hypothyroidism. This approach of L-thyroxine therapy could reduce EPO dosage, and improve both anemia and clinical symptoms.Whether the identified HD patients with hypothyroidism should be treated with L-thyroxine for the action of EPO on the bone marrow or left untreated for energy conservation is worth further investigation. The aim of this study is to investigate the effect of L-thyroxine on clinical manifestations and EPO responses, and the approach to L-thyroxine dosage adjustment for HD patients with Incidental hypothyroidism. Methods Thyroid function test, definitions of hypothyroidism and Incidental hypothyroidismVenous blood samples were drawn immediately before HD and sent to the central laboratory at TVGH for measurement of serum