Blood Volume in Hyperthyroidism.

Abstract

It is a well recognized fact that many patients with hyperthyroidism have disturbances of their cardiovascular system. With the increased demand for oxygen some compensatory mechanism must be at work in order to supply the needs of the tissues. The cardiac output and the velocity of blood flow have been repeatedly shown to be increased, and as a rule, this increase is in direct proportion to the basal metabolic rate. 1 , 2 In the opposite condition, myxedema, Thompson 3 described a reduction in the blood volume and demonstrated its return to normal after the institution of thyroid treatment. Blotner, Fitz and Murphy 4 also observed a correlation between the basal metabolic rate and the total blood count expressed in corpuscles per square meter of surface area. The present report deals with the blood volume findings in individuals suffering from hyperthyroidism, before and after subtotal thyroidectomy.

The series studied consisted of 17 cases of exophthalmic goiter and one of toxic adenoma.∗ The total blood volume was measured by the carbon monoxide method. 5 All the determinations were made in the afternoon about 3 hours after the noon meal. Patients with fever and organic lesions of the heart were excluded. The results are expressed in cc. of blood per kg. of body weight. The minimum blood volume was 58 cc. per kg. and the maximum, 115 cc., with an average volume of 77.3 cc. The average total blood volume in normal individuals studied with the same method was 66.6 cc. (6)

The blood volume of 14 patients was again determined after their basal metabolism returned to normal following subtotal thyroidectomy. The time between the operation and the determination varied from 10 days to 5 months, and some patients had repeated measurements.