Pretreatment prevalence of hypothyroidism in patients with head and neck carcinoma

BACKGROUND. Hypothyroidism in the normal population age > 60 years is encountered in the range of 0.5-5% clinically, and 5-20% have subclinical hypofunction. Hypothyroidism is recognized as a common complication of treatment in patients with head and neck carcinoma (HNC) and is reported in up to 75% of patients who receive combined treatment. Surprisingly, base-line pretreatment measurements of thyroid function in large series of patients have not been reported. METHODS. Serum thyroid-stimulating hormone, free T4, and total T3 levels were recorded in 110 patients with nonthyroid HNC prior to treatment in a prospective, controlled study. RESULTS. The mean patient age (± standard deviation) was 65 years ± 13.8 years, and 82% of patients had squamous cell carcinoma. A diagnosis of hypothyroidism already was established in 4.5% of patients, and subclinical hypothyroidism was discovered in an additional 6.4% of patients. Sixteen patients had other equivocal anomalies in thyroid function and were referred for further endocrine evaluation. No patients with formerly unrecognized clinical hypothyroidism were found. CONCLUSIONS. Hypothyroidism in patients with head and neck carcinoma in Israel corresponds with the reported incidence in the general population. Hypothyroidism after treatment for head and neck carcinoma stems from the effects of treatment. The need for pretreatment evaluation of thyroid function should be considered.