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Biomedical subjects

L Shenkman

Publications and source records attributed to L Shenkman.

112 records · Page 7Linked to original sources
PubMedDate not supplied

Measurements of free and total serum T3 and T4 in pregnant subjects and in neonates.

Despite recent descriptions of dramatic changes in the thyroidal economy in pregnancy, the precise mechanisms of these alterations have remained obscure. Measurements of total and free triiodothyronine (T3) and thyroxine (T4) and thyroxine binding capacity (TBG) were made in 120 serum samples from 42 first trimester, 55 second trimester, and 23 third trimester pregnant women. Sixteen paired term and cord blood samples were also analyzed. Mean total serum T4 rose progressively from 9.8 in the first trimester to 11.5 mug/100 ml in the third trimester. Mean TBG capacity also increased from 38.4, first trimester, to 56.2 mug/100 ml in the third trimester. Mean total T3 concentrations were significantly elevated in all trimesters (p less than 0.02 - 0.0011) when compared to normal nonpregnant controls. Total T3, T4 and TBG levels were all significantly higher than in normal nonpregnant women in all trimesters (p less than 0.001). TSH levels remained unchanged in all three trimesters; values were 2.2, 2.0, and 2.0 muU/ml, respectively. Free T4 levels were at the lower limits (2.4, 2.5, and 2.2 ng/100 ml) and free T3 levels were below normal (0.29, 0.27, and 0.24 ng/100 ml). In addition, fetal T3 concentrations were strikingly lower in cord blood than in the maternal circulation at term. Maternal and cord free T3 and free T4 levels were not significantly different. These data underscore the need for multiple measurements of thyroid function in pregnancy and in the newborn in the evaluation of the thyroid gland activity.

Female↗
PubMedDate not supplied

Noonan's syndrome and hypopituitarism.

A 37-year-old man with Noonan's syndrome hypopituitarism is described. The patient had small stature, minor facial abnormalities, cubitus valgus and pectus excavatum. In addition, endocrine testing revealed deficiencies of growth hormone, gonadotrophins and TSH. Prolactin increased normally in response to TRH administration, but failed to rise after chlorpromazine. Although intrinsic pituitary dysfunction cannot be excluded, the dissociated response of prolactin to TRH and chlorpromazine suggests that the pituitary hormone deficiencies may be secondary to hypothalamic dysfunction.

Adult↗
PubMedDate not supplied

Thyroid function in the elderly.

Thyroid dysfunction is common in older individuals, yet the diagnosis is often complicated by atypical clinical presentations and difficulty in interpretation of laboratory tests. An understanding of the alterations in thyroid function occurring normally as a consequence of the aging process is necessary for correct laboratory diagnosis of thyroid dysfunction in the elderly. There are subtle alterations in hypothalamic and pituitary function but normal feedback control of TSH secretion persists. In the thyroid itself, morphologic changes develop with age, but have little impact on thyroid hormone economy. Thyroidal secretion of thyroxine decreases, but parallels the decrease in thyroxine degradation rate, resulting in unaltered plasma thyroxine levels. Decreased peripheral conversion of thyroxine to triiodothyronine causes a fall in triiodothyronine concentrations. Nonthyroidal illnesses in the elderly may perturb the laboratory assessment of thyroid function by producing isolated high or low thyroxine levels in euthyroid individuals.

Adult↗