Primary hypothyroidism

About: Primary hypothyroidism is a research topic. Over the lifetime, 1972 publications have been published within this topic receiving 35650 citations.

Overt and Subclinical Hypothyroidism Complicating Pregnancy

Abstract: We studied the evolution of 150 pregnancies corresponding to 114 women (16‐ 39 years old) with primary hypothyroidism. Fifty-one pregnancies (34%) were conceived under hypothyroidism: 16 overt (X 6 standard deviation [SD], thyroxine [T 4]: 2.44 6 0.7 mg/dL; thyrotropin [TSH]: 33.4 6 8.82 mIU/L), and 35 subclinical hypothyroidism (T 4: 6.93 6 1.88 mg/dL; TSH: 12.87 6 8.43 mIU/L); 99 pregnancies were conceived under euthyroidism while undergoing thyroid therapy. When treatment with levothyroxine was inadequate, the outcome of pregnancy was abortion in 60% of overtly hypothyroid patients and in 71.4% of subclinically hypothyroid patients, premature delivery in 20% and 7.2% respectively, and term delivery in 20% and 21.4%, respectively. When treatment was adequate, 100% of overtly hypothyroid patients and 90.5% of subclinically hypothyroid patients carried pregnancies to term; there were no abortions in any of the groups. Abortions, premature and term deliveries in patients who were euthyroid on levothyroxine at the time of conception were 4%, 11.1% and 84.9% respectively. Of the patients receiving levothyroxine therapy before conception, 69.5% had to increase the dose (mean increase 46.2 6 29.6 mg/d). Of 126 evaluated newborns, 110 were delivered at term while 16 were premature. Eight newborns, 4 were premature, had congenital malformations (6.3%), and 4 died. Our results show that the evolution of pregnancies did not depend on whether the hypothyroidism was overt or subclinical but mainly on the treatment received. The adequate treatment of hypothyroidism during gestation minimizes risks and generally, makes it possible for pregnancies to be carried to term without complications.

Severe hypothyroidism caused by type 3 iodothyronine deiodinase in infantile hemangiomas.

Abstract: Hemangiomas are the most common tumors of infancy, with a prevalence of 5 to 10 percent among one-year-olds. They are characterized by rapid growth in the first year of life, followed by involution and gradual regression by adolescence.1,2 We recently treated a three-month-old infant with massive hepatic hemangiomas and primary hypothyroidism who needed very high doses of thyroid hormone to restore euthyroidism and normal thyrotropin secretion. This finding suggested that the rate of degradation of thyroid hormone was accelerated. We subsequently identified high levels of type 3 iodothyronine deiodinase activity in the hemangioma tissue. This selenoenzyme, normally present in . . .

The effect of age on prevalence of secondary forms of hypertension in 4429 consecutively referred patients.

Abstract: OBJECTIVES To investigate the importance of age and other variables on the prevalence of secondary forms of hypertension in a hypertension referral center. DESIGN Over the past 18 years 4429 patients have been referred by their physicians for a 1-day blood pressure study to investigate secondary causes of hypertension. METHODS The 1-day blood pressure study included a history and physical examination by a physician, and measurements of serum sodium, potassium, creatinine, thyroxine, thyroid stimulating hormone, stimulated plasma renin activity, blood pressure response to the angiotensin II analogue saralasin, recumbent and upright plasma catecholamines, and plasma cortisol and aldosterone after infusion of 2 liters 0.9% saline over 3-4 h. RESULTS The prevalence of secondary forms of hypertension was 10.2%, including renovascular hypertension (3.1%), primary aldosteronism (1.4%), Cushing's syndrome (0.5%), pheochromocytoma (0.3%), primary hypothyroidism (3.0%) and a serum creatinine > 2.0 mg/dl (1.8%). There was a very significantly increased prevalence with age of secondary forms of hypertension associated with renovascular hypertension, primary hypothyroidism and renal insufficiency. The concomitant presence of atherosclerosis significantly increased the prevalence of renovascular hypertension (9.5%) and renal insufficiency (8.0%). CONCLUSIONS Increasing age and coexisting atherosclerosis have significant effects on the prevalence of secondary forms of hypertension.

Euthyroid Sick Syndrome: Is It a Misnomer?

Abstract: Alterations in thyroid function tests are very common in patients with NTI. Multiple, complex, and incompletely understood mechanisms are involved in these abnormalities. Knowledge of these abnormalities is necessary to avoid errors in the diagnosis of thyroid disease. Measurement of serum TSH, free T4, and free T3 levels by direct equilibrium dialysis/RIA methods probably yield most useful (accurate) information in the setting of NTI. Patients with low free T4 by these methods and normal or low TSH have secondary hypothyroidism. This may be due to NTI per se, drugs administered for treatment of NTI, or associated pituitary or hypothalamic disease; the latter consideration may require evaluation of cortisol reserve, PRL, and/or gonadotropins. A serum TSH level above 20-25 microU/mL probably reflects primary hypothyroidism; accompanying findings of goiter, low free T4, and positive antithyroid antibodies help establish the diagnosis. An elevated serum concentration of rT3 argues against hypothyroidism. Studies have demonstrated no discernible benefit of treatment of NTI patients with T4. Some studies have shown a few benefits of treatment with T3 in selected cases, but much more needs to be learned. There is no evidence of harm by treatment of NTI patients with up to replacement doses of T3. As some NTI patients may indeed be hypothyroid, the term ESS should be replaced with NTIS.