Hypofunction of the thyroid gland - congenital hypothyroidism (cretinism)

Hypothyroidism is one of the most common endocrine problems of childhood. It can be congenital, for example, in a nerd or acquired, for example, from autoimmunization (Hashimotos thyroiditis). Hypothyroidism from dietary iodine deficiency is rarely seen today, because the use of iodized salt made it easy to get a source of nutrients.

Congenital hypothyroidism (cretinism)
Cretinism is usually caused by the failure of the embryonic development of the thyroid gland, but it can also be the result of congenital enzymatic defects in the synthesis of thyroxin. The severity of the disorder depends on the presence of thyroid tissue. Usually the newborn does not show obvious signs of hypothyroidism, probably due to an exogenous source of thyroid hormones supplied by the maternal circulation. Manifestations are delayed in infants.

In another type of cretinism, goytingen transfer (substances that can cause goiter), such as antithyroid drugs phenylbutazone, para-aminosalicylic acid. And cobalt can inhibit the secretion of the thyroid gland, which leads to congenital cretinism. Although the latter is self-limiting, it is a potentially bad condition, because as soon as the maternal delivery stops, the thyroid newborn cannot produce its own hormones. In addition, a large goiter in a newborn can cause a complete obstruction of the airways.

Clinical manifestations of congenital hypothyroidism
Symptoms of cretinism usually appear between the ages of 3 and 6 months in children who are breastfeeding. However, until this time, the earliest symptoms indicating hypothyroidism include prolonged physiological jaundice, feeding difficulties, inactivity (excessive sleep and minimal crying), anemia, and problems resulting from hypotonic abdominal muscles such as constipation, rectal diastasis, protruding abdominal and umbilical hernia. Behavioral characteristics often lead parents to describe the baby as exclusively “calm and good”,

Impaired development of the nervous system leads to mental retardation. The severity of intellectual deficiency is associated with the degree of hypothyroiditis and the duration of the condition before treatment. Other manifestations of the nervous system include slow, uncomfortable movements, drowsiness, lethargy, and abnormal deep tendon reflexes, often called “hangs,” because the relaxation phase after contraction is slow.

Because skeletal growth lags far behind, the baby is short. Unlike pituitary carlism, infantile proportions are preserved by the fact that the length of the trunk remains in strengthening and often leads to obesity. Characteristic infantile features of myxedema include a short forehead, wide swollen eyes, wrinkled eyelids, a wide, short, upturned nose and a large protruding tongue. The hair is often dry, fragile or matte and follow the hair. The dental nerve is delayed and usually defective. This facial feature gives the child a characteristic boring expression. The skin is yellowish from carotemia as a result of depression of the hepatic conversion of carotene into vitamin A. The loss of heat from a decrease in metabolism is reflected in cool skin. Cold intolerance is another general consensus. Anemia leads to pallor, fatigue and lethargy, and vitamin A deficiency causes thickening, rough, dry, scaly skin.

Cardiovascular changes - slow pulse, decrease in blood circulation, spotting and decrease in pulse. Reduced heart rate and power are directly related to a decrease in oxygen demand with a low metabolic rate. Respiratory changes include intense shortness of breath and decreased respiratory effort.

In breastfed infants, clinical manifestations can be postponed until the baby is weaned, and during this time, signs of the face, changes in skin and hair, growth retardation, hypotension and cardiovascular changes will appear. Since breast milk contains sub-quantities of thyroid hormones, the age of the bones is very backward, usually comparable to the age of the newborn. It is noteworthy, however, that intellectual functioning remains almost normal.

Diagnostic evaluation
There are several tests to evaluate the activity of the thyroid gland:
• Measurement of protein bound iodine (PBI)
• Measurement of free thyroxine
• Measurement of thyroid stimulating hormone
• Measurement of thyrotropin release factor, radioimmunoassay of thyroxine and triiodothyronine.

These tests measure the amount of secreted thyroid hormone and the repulsion of homeostatic mechanisms. Tests of thyroid function usually include an oral infusion of a radioactive isotope iodine-131. Neonatal screening is now possible with a highly sensitive and specific radioimmunoassay for thyroxine and thyroid stimulating factor and low thyroxine levels in the first days of life. Radiography is used to estimate bone age.

Therapeutic management
Treatment includes unspecified replacement therapy with a dried thyroid gland to cancel all signs of hypothyroidism and restore normal physical and mental development. If a suitable replacement for thyroid hormone begins before the age of 3 months, the probability of a normal IQ increases. To avoid the risk of overdosing thyroid hormones, regular evaluations of thyroxine and triiodothyronine levels should be evaluated. Surveys of age-related changes are also conducted to ensure optimal growth.