Low maternal plasma fT4 concentrations during early pregnancy may be an important risk factor for impaired infant development.
During illness, major changes in thyroid hormone metabolism and regulation occur; these are collectively known as non-thyroidal illness and are characterized by decreased serum triiodothyronine (T 3 ) and thyroxine (T 4 ) without an increase in serum TSH. Whether alterations in the central part of the hypothalamus-pituitary-thyroid (HPT) axis precede changes in peripheral thyroid hormone metabolism instead of vice versa, or occur simultaneously, is presently unknown. We therefore studied the timecourse of changes in thyroid hormone metabolism in the HPT axis of mice during acute illness induced by bacterial endotoxin (lipopolysaccharide; LPS).LPS rapidly induced interleukin-1 mRNA expression in the hypothalamus, pituitary, thyroid and liver. This was followed by almost simultaneous changes in the pituitary (decreased expression of thyroid receptor (TR)-2, TSH and 5 -deiodinase (D1) mRNAs), the thyroid (decreased TSH receptor mRNA) and the liver (decreased TR 1 and D1 mRNA). In the hypothalamus, type 2 deiodinase mRNA expression was strongly increased whereas prepro-TRH mRNA expression did not change after LPS. Serum T 3 and T 4 fell only after 24 h.Our results suggested almost simultaneous involvement of the whole HPT axis in the downregulation of thyroid hormone metabolism during acute illness.
Background: Iodine deficiency and endemic goiter have been reported in the past in The Netherlands, especially in the southeast. Objective: To evaluate iodine intake and thyroid size in Dutch schoolchildren, contrasting those living in a formerly iodine-deficient region in the east (Doetinchem) with those living in an iodine-sufficient region in the west (Amsterdam area). Design: Cross-sectional survey of 937 Dutch schoolchildren aged 6±18 years, of whom 390 lived in the eastern and 547 in the western part of the country. Methods: Thyroid size was assessed by inspection and palpation as well as by ultrasound. Iodine intake was evaluated by questionnaires on dietary habits and by measurement of urinary iodine concentration. Results: Eastern and western regions were similar with respect to median urinary iodine concentration (15.7 and 15.3 mg/dl, NS, Mann-Whitney U test), goiter prevalence by inspection and palpation (0.8 and 2.6%, P 0X08, chi-squared test), and thyroid volumes. The P97.5 values of thyroid volumes per age and body surface area group were all lower than the corresponding sexspecific normative WHO reference values. Iodized salt was not used by 45.7% of households. Daily bread consumption was five slices by boys and four slices by girls. Weekly milk consumption was 3 liters by boys and 2 liters by girls. Seafish was consumed once monthly. From these figures we calculated a mean daily iodine intake of 171 mg in boys and 143 mg in girls, in good agreement with the measured median urinary concentration of 16.7 mg/dl in boys and 14.5 mg/dl in girls. The sex difference in iodine excretion is fully accounted for by an extra daily consumption of one slice of bread (20 mg I) and one-seventh of a liter of milk (8.3 mg I) by boys. Thyroid volume increases with age, but a steep increase by 41% was observed in girls between 11 and 12 years, and by 55% in boys between 13 and 14 years, coinciding with peak height velocity. Girls have a larger thyroid volume at the ages of 12 and 13 years, but thyroid volume is larger in boys as of the age of 14 years. Conclusions: (1) Iodine deficiency disorders no longer exist in The Netherlands. (2) Bread consumption remains the main source of dietary iodine in The Netherlands; the contribution of iodized table salt and seafish is limited. (3) The earlier onset of puberty in girls renders their thyroid volume larger than in boys at the age of 12±13 years, but boys have a larger thyroid volume as of the age of 14 years.
The case history of a 56-year-old man is described who suffered from severe adrenocorticotrophic hormone (ACTH)-dependent Cushing's syndrome. The clinical course was complicated by simultaneous infections with Pneumocystis carinii, Staphylococcus aureus, Candida albicans, Aspergillus fumigatus and Herpes simplex, which proved to be fatal. A study of the literature shows that opportunistic infections in endogenous Cushing's syndrome are associated with severe cortisol excess and carry a high mortality. Opportunistic infections are most prevalent in the ectopic ACTH syndrome explained by the very high plasma cortisol concentrations in this condition. Infections with Aspergillus species, Cryptoccus neoformans, Pneumocystis carinii and Nocardia asteroides predominated. Cushing's syndrome with a very high plasma cortisol concentration causes a severe immunocompromized state. Prompt evaluation of the cause of the hypercortisolism, initiation of cortisol lowering therapy, primary prophylaxis for Pneumocystis carinii infection when plasma cortisol exceeds 2500 nmol L-1 and a search for concomitant infectious disease is recommended.
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