D. A. Koutras

Endothelial dysfunction of conduit arteries in insulin-dependent diabetes mellitus without microalbuminuria

OBJECTIVE Previous studies have shown that endothelial dysfunction, an early sign of atherosclerosis, occurs in animal models of diabetes mellitus and in resistance vessels of patients with insulin-dependent diabetes. In the present study we examined whether young patients with insulin-dependent diabetes without microalbuminuria present abnormal endothelial function of large peripheral arteries. METHODS Twenty-six patients with insulin-dependent diabetes without microalbuminuria were compared with 26 normal controls and 5 patients with insulin-dependent diabetes with microalbuminuria. Brachial artery diameter was measured at rest, during reactive hyperaemic flow (endothelium-dependent dilatation) and after sublingual isosorbide dinitrate (endothelium-independent dilatation). RESULTS Baseline artery diameter and flow as well as the degree of reactive hyperaemia were similar in all groups compared to controls. Flow-mediated dilatation was lower in patients with diabetes without microalbuminuria (5.8 +/- 7 vs 11 +/- 7%. P = 0.01) as well as in patients with diabetes without microalbuminuria (0.75 +/- 2.5 vs 11 +/- 7%, P = 0.003); nitrate-induced dilatation was normal in patients without microalbuminuria and attenuated in patients with microalbuminuria. In the group of diabetes patients without microalbuminuria, those with disease duration > 10 years and HbAlc > 6% had the worse endothelial function. CONCLUSIONS Our results demonstrate that endothelial dysfunction of conduit arteries can be detected in patients with insulin-dependent diabetes mellitus without microalbuminuria, probably contributing to the high prevalence of atherosclerosis in these patients.

Iodine Metabolism in Chronic Renal Insufficiency

Iodine metabolism has been studied in 20 patients with advanced chronic renal insufficiency due to primary renal disease, and thyroxine turnover in another 5 similar patients. Comparatively to 18 cont

THE TOXIC EFFECTS OF SMALL IODINE SUPPLEMENTS IN PATIENTS WITH AUTONOMOUS THYROID NODULES

In sixteen cases of toxic adenoma of the thyroid (autonomous hot nodule with complete suppression of the surrounding normal parenchyma) potassium iodide was given in doses of 100 μg/day for one week, 200 μg/day for another and 400 jug/day for a third week. There was a progressive increase in the serum T4 level. Serum T3 also increased, although this was significant only after the first week. Serum TSH was undetectable throughout the entire period of the study. This metabolic pattern is different from the response seen in cases of nontoxic endemic goitre, where small iodine supplements induce an increase in serum T4 but a decrease in serum T3. Furthermore, the present results may explain the phenomenon of iodineinduced or iodine‐precipitated hyperthyroidism (Jod‐Basedow) when patients with autonomous thyroid are presented with a high iodine intake. In contrast to the results obtained with small iodide doses, two other cases treated with large pharmacological doses of iodide showed a decrease in both serum T4 and serum T3. It is concluded that the physician should be aware of the possibility of precipitating or aggravating thyrotoxicosis in patients with an autonomous hot nodule by increasing their intake of iodine.

PITUITARY AND THYROID INSUFFICIENCY IN THALASSAEMIC HAEMOSIDEROSIS

Thyroid and pituitary function tests using hypothalamic releasing factors were performed in seven patients with thalassaemia and secondary haemosiderosis and in a control group of seven healthy subjects. The TSH level in the thalassaemic patients (18.07± 1.10 μU/ml) was higher than in the controls (1.01±0.14 μU/ml, P<0.001). After TRH administration the TSH values increased less than in the controls. Serum thyroxine and FT4I values were lower in the group of patients with thalassaemia (76.7 ± 7.8 nmol/1 and 19.3 ± 2.2) compared to the controls (116.1±6.9 nmol/1, P <0.005 and 38.6 ± 3.6, P <0001). The basal prolactin values did not differ significantly between the two groups, but after TRH administration the increment was significantly lower in thalassaemics than in controls (P <0.005). The basal LH values were lower in the thalassaemic patients (1.37±0.24 ng/ml) than in the controls (3.23 ± 0.50 ng/ml) and did not increase significantly after LHRH administration. The FSH values were also lower in the thalassaemic group (0.46±0.15 ng/ml) compared to the controls (2.06±0.08 ng/ml, p <0.001), and increased only slightly after LHRH administration. We conclude that in thalassaemia pituitary deficiency exists, mostly of gonadotrophs, but possibly also for the thyrotrophs and the lactotrophs. Latent primary hypothyroidism has also been found in the thalassaemic group. The functional abnormalities found in both endocrine glands are best explained as a consequence of coexisting haemosiderosis.

IODINE METABOLISM IN AUTONOMOUS HOT NODULES OF THE THYROID

The thyroidal iodide clearance rate, the plasma inorganic iodine (PII), the absolute iodine uptake (AIU) by the thyroid, the serum PBI, the intrathyroidal exchangeable iodine pool, the renal iodide clearance rate and the urinary iodine excretion were measured in twenty‐one cases of autonomous hot thyroid nodule with suppression of the normal parenchyma (toxic adenoma, TA), in eight cases of autonomous hot nodule without such suppression (subtoxic adenoma, STA), and in eighteen controls; the 131 I uptake and PB131 I were measured in 390 cases of TA and 111 of STA compared with eighty‐one controls.

Lack of Influence of Povidone-Iodine on Tests of Thyroid Function

The external application of povidone-iodine, an antiseptic agent, was tested for its influence on thyroid function. Previous workers have described some in vitro changes in thyroid function tests following its use. In the present study topical application of povidone-iodine did not affect thyroid function as measured some days later using both in vivo and radio-active iodine in vitro test methods, despite the fact that the latter are notorious for being influenced by exogenous iodine.

One swollen hand

A 34-year-old woman first complained of a swollen right hand in November, 1996. The swelling was on the back of the hand and on her right forearm. It was painless and not tender, but gradually got worse. It was originally considered to be lymphoedema, and she had a series of investigations in search of a space-occupying lesion, including magnetic resonance imaging of her chest. All tests for inflammation and collagen disease were negative. She was readmitted to hospital 2 years later, in February, 1999 because the swelling was still present, although it had recently started to go down.