Changes in biochemical parameters during complete thyroid hormone deficiency of short duration in athyreotic patients

The effect of withdrawal of suppressive therapy with thyroid hormones (200 micrograms L-thyroxine/day) on serum biochemical profiles and blood cell counts were studied in ten athyreotic thyroid carcinoma patients. After 14 days off therapy, all patients but one were still clinically and biochemically euthyroid. Twenty-eight days without thyroid hormones resulted in severe clinical and biochemical (TT4, TSH) hypothyroidism. At that time, the following parameters changed significantly: CPK activities increased (in five of ten patients above normal) as well as activities of SGOT, SGPT, and LDH (means and s.d.s within the respective normal ranges). Total cholesterol and triglycerides increased within the normal range. There were minimal but significant increases of serum creatinine and of mean corpuscular volume of erythrocytes as well as decreases of serum sodium and calcium. Our study underlines the importance of further investigation if pathologic biochemical or hematologic parameters are obtained in athyreotic patients after 4 wk withdrawal of thyroid hormone therapy.