Thyroid volume was measured by ultrasonography in 50 healthy adults (25 males, 25 females, age 20-70 years) living in the non-iodine deficient area of Amsterdam. Thyroid volume was 10.7 +/- 4.6 ml (mean +/- SD, range 2.7-20.4 ml). No relation was found between thyroid volume and any of the following parameters: plasma TSH, T4, T3, thyroglobulin (Tg), urinary iodine excretion, tobacco and alcohol consumption. Thyroid volume in males (12.7 +/- 4.4 ml) was greater than in females (8.7 +/- 3.9 ml, p = 0.0014), but no sex difference was observed in the ratio of thyroid volume to body weight (males, 0.16 +/- 0.05 ml/kg; females 0.13 +/- 0.06 ml/kg; NS). Thyroid volume was positively related to body weight, but not to age. We conclude that the sex difference in thyroid volume is due to the difference in body weight between males and females. Lean body mass is presumably the most important physiological determinant of thyroid size in subjects living in a non-iodine deficient area.

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After intravenous injections, we have found the immunological half-life of purified porcine proinsulin to be more prolonged than purified porcine single-component insulin in both swine (22 and 9 min, respectively) and in baboons (18 and 8 min, respectively). Studies in humans have also indicated a longer half-life of proinsulin than insulin (1). These findings have prompted the present investigation of the in vitro degradation of insulin, proinsulin, and the connecting peptide that links the A and B chains of insulin in the proinsulin molecule, using an isolated liver perfusion system.Methods. Intact livers, weighing 4.5-6.8 g, from male Wistar rats, fasted for 48 hr, were cyclically perfused by the method of Hems et al. ( 2 ) . The perfusion fluid consisted of washed human erythrocytes, 2 g/lOO ml bovine serum albumin (Cohn, Fraction V ) , and Krebs-Henseleit buffer, pH 7.4, with a hemoglobin concentration of approximately 3 g/lOO ml. After complete isolation from the circulation, the livers were perfused in situ by adjusting the hydrostatic pressure of the perfusate to give maximal perfusion rates without liver swelling. This was approximately 2-3 ml/g wet weight of liver. The total perfusion volume was 150 ml at the beginning of the experiment. After a 40-min equilibration period, purified porcine single-component insulin (Lilly ), proinsulin (Lilly ), or con-

The effect of the beta-adrenoceptor blocking agent propranolol on plasma levels of thyroxine and triiodothyronine was studied in eleven hyperthyroid patients and in six hypothyroid patients on L-thyroxine substitution therapy. In all patients a decrease in plasma-triiodothyronine was found. The per cent decrease of plasma-triiodothyronine was the same in both groups. Plasma levels of thyroxine and thyrotropin increased in the hypothyroid patients, but remained constant in the hyperthyroid subjects. The decrease in plasma-triiodothyronine during propranolol medication is most likely caused by an inhibition of the peripheral conversion of thyroxine into triiodothyronine.

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To study the long-term outcome after thyroidectomy, 113 sporadic non-toxic goitre patients who underwent thyroidectomy in our hospital in the period 1974-1983, were studied. Five patients complained of recurrent goitre; a goitre was found on inspection and palpation in these five and in 15 others. There were no differences between the 20 patients with goitre and the 93 patients without goitre with regard to sex, age, duration of goitre, indication and type of thyroidectomy, postoperative thyroid hormone medication, period of follow-up, and T4, T3, or TSH plasma values at the time of follow-up examination. Twenty-three patients complained of voice changes since thyroidectomy. In a case control study, included in this follow-up study, 19 patients with goitre, i.e. thyroid size I and II as estimated by inspection and palpation (cases), and 16 patients without goitre, i.e. thyroid size OA and OB (controls), were studied in more detail. No difference between cases and controls was found in any of the above mentioned parameters that could explain the recurrence of goitre. Thyroid volume (median) was greater in the cases (34.1 ml, range 7.9-83.4) than in the controls (10.3 ml, range 2.5-48.7) (P less than 0.001), although a considerable overlap between the two groups was observed. One or more thyroid nodules were found in 89.5% of the cases and in 62.5% of the controls (NS). Serum thyroid growth stimulating immunoglobulin (TGI) was present both in cases (68%) and controls (50%). TGI was present in high titres in all five patients who complained about recurrent goitre.(ABSTRACT TRUNCATED AT 250 WORDS)

PRL was measured radioimmunologically in plasma and cerebrospinal fluid (CSF) samples obtained simultaneously in 31 patients with various neurological or infectious, but non-endocrine diseases (group A), 12 patients (7 pregnant women and 5 newborns) with physiological hyperprolactinemia (group B),10 psychiatric patients with pharmacologically induced hyperprolactinemia (group C) 12 normoprolactinemic patients with pituitary adenoma and suprasellar extension (SSE) (group D), And 14 hyperprolactinemic patients with pituitary adenoma with and without SSE (group E). Plasma PRL and CSF PRL concentrations (ng/ml, mean and range in brackets) of the various groups were: group A, 6.2 (1.3-14.5) and 1.3 (0.6-4.7); group B, 85.2 (31-200) and 13.2 (3-28); group C, 54.3 (3.5-160) and 6.5 (0.7-18); group D, 17.2 (5.4-30) and 9.7 (2.7-34); and group E, 2,529 (115-10,000) and 1,449 (6-13,000). The plasma to CSF concentration ratios (mean and range in brackets) were: group A, 5.2 (1.4-13.0); group B, 7.0 (2.9-10.3); group C, 7.3( 3.9-11.3); group D, 2.6 (0.9-7.1); and group E, 10.9 (0.2-34.9). The ratio was greater than 3 in 87% of the non-tumor patients; in 42% of the tumor patients the ratio was less than 3. The correlation between plasma and CSF PRL levels of all 53 subjects without a pituitary tumor (groups A, B, and C) was positive (r=0.9097; P=0.00001); in the 26 tumor patients (groups D and E) the correlation was also positive (r=0.7141; P=0.00002). These results indicate that 1) PRL is a normal constituent of CSF, 2) the CSF PRL level is a function of the plasma level, 3) detectable, or even high, CSF PRL levels per se are not indicative in the presence of a pituitary tumor, with or without SSE, and 4) abnormally low ratios may be found in patients with a pituitary tumor with SSE.