Hypothyroidism
	Huber et al., Basel, Switzerland, reported a prospective study in 154 females with subclinical hypothyroidism. The risk factor for developing overt thyroid failure was estimated during a mean observation period of 10 years. In addition to serum TSH, thyroid reserve (delta T3 after TRH) and thyroid autoantibodies were measured. Three groups of patients were discerned i.e. TSH < 6 mU/l (gr I); TSH 6-12 mU/l (gr II); TSH >12 mU/l (gr III). These 3 groups were subdivided according to normal or subnormal thyroid reserve and presence or absence of thyroid autoantibodies. It appeared that in group I the risk factor was maximally 1.8 and varied very little between the subgroups. In group II there was neither a great variation in the different subgroups with regard to the risk factor of developing overt hypothyroidism. This factor varied between 3 and 5. In group III the risk factor varied between 17 and 23 in all subgroups when at least one other abnormality was present i.e. a decreased thyroid reserve or the presence of autoantibodies. A combination of two of these factors did not increase the risk. The risk factor of developing overt hypothyroidism was 13, namely when both thyroid reserve was normal and thyroid autoantibodies were absent. (Comment: The most remarkable finding in this study is, that apparently the presence of circulating thyroid autoantibodies hardly influences the risk factor of developing overt hypothyroidism while many other studies just show the opposite in that the presence of autoantibodies markedly increase this risk factor.) Piperingos et al., Athens, Greece, investigated the prevalence of sideropenia in 13 patients with overt hypothyroidism (OH), 45 patients with subclinical hypothy-roidism (SH), and 59 sex- and age-matched euthyroid controls (EC). In OH they found in 7/13 patients low levels of Fe and ferritin and increased Fe-binding capacity. In SH 14/45 were sideropenic while this was 6/59 in EC. Eight patients with SH were treated with 80 mg Fe+++/daily for 3 months after which mean TSH decreased from 5.4 ± 1.8 mU/l to 4.5 ± 1.7 mU/l, the statistical significance of which was not reported. Danese et al., Rome, Italy, performed TSH screening in 4036 male flying personnel, between 25 and 73 years (mean age 34.3 years) who had yearly check-up. Subjects with disorders or treatment known to interfere with thyroid function testing were excluded. Serum TSH levels were increased in 1.1% of subjects, all having normal-low serum levels of T4 and FT4. Of these 45 subjects, 18 were positive for TPOAb and 8 of them were over 65 years; 22/45 had elevated serum cholesterol. It was experimentally shown that a lower efficiency, particular in logic memory and spatial and temporal sense of locality and a modification in behaviour with higher index of neurosis was present in subjects with subclinical hypothyroidism as compared to matched controls. (Comment: Ask the pilot for his serum TSH before embarking!) Tielens et al., Rotterdam, The Netherlands, performed multigated equilibrium radionuclide ventriculography in 62 consecutive patients with hypothyroidism without clinical and an echocardiographic cardiac disease. Their main findings were that in hypothyroidism the most sensitive cardiac parameters in rest were the time to peak emptying and filling, indicating that thyroid hormone notably affects the velocity of contraction and the velocity of active relaxation. They also found that diastolic function rather than overall systolic cardiac function is influenced by hypothyroidism. (Comment: These phenomena found in heart function in hypothyroid patients remind me of the same phenomena found with regard to ankle reflex time. Is the pathophysiology also similar?) Danese et al., Baltimore, MD, USA, did a meta-analysis of literature concerning the effect of T4 treatment in subclinical hypothyroidism on serum lipids. After careful critical analysis they found on the basis of 14 studies that significant favourable changes occur in serum lipid concentrations (decrease of total cholesterol and LDL-cholesterol, and increase of HDL- cholesterol) when patients with subclinical hypothyroidism are treated with T4. (Comment: It seems to me that the burden to proof a correct attitude towards subclinical hypothyroidism has now shifted to those who withhold T4 administration rather than to those who treat these patients with T4.) Mandel et al., Jamaica Plain, MA, USA, found in a study including 335,150 newborns, that the incidence of congenital hypothyroidism (CH) in infants with a birth weight <2500 gm (gr I) was 1:703, and in infants >2500 gm (gr II) 1:3051. The authors also calculated the positive predictive value (PPV) of various TSH ranges for the diagnosis of CH on the basis of 1607 infants who had elevated initial TSH. Their data suggest that there is a 4-fold higher incidence of CH in infants less than 2500 gm weight, manifested both by immediate or delayed TSH elevations. Furthermore a screening TSH of 20-39.9 mU/l is 6.4 times more likely to be diagnostic of CH in low birth weight infants than in those weighing >2500 gm, and lastly, a PPV of a TSH >80 mU/l is 99% in healthy newborns >2500 gm.