Cretinism: Symptoms, Causes and Treatment

Cretinism is a medical condition in which hypothyroidism occurs early in life. It is a disease of thyroid gland where levels of thyroid hormones in the blood is low(hypothyroidism) since birth. If left untreated it can cause stunted physical and mental growth. It is also known as congenital hypothyroidism.

It usually affects every one out of 3000 live births and more prevalent in mountainous area like Himalayas, inland China or Africa.

Thyroid Hormone

Thyroid gland is a butterfly shaped organ located at the lower portion of the neck and whose main function is to produce the thyroxine hormones. Iodine and presence of certain enzymes are essential for the production of thyroxine hormones. These hormones are responsible for the regulation of body growth, overall metabolism and brain development.

Signs and Symptoms of Cretinism

The signs and symptoms of cretinism can vary depending on age of onset.

• Early signs of infancy
• Slow movement
• Development of dry skin
• Drooling from an open mouth
• Abnormal physical characteristics
• Short and wide face
• Low hair line
• Underdeveloped lower jaw
• Overdeveloped upper jaw
• Tongue which is thick, large and protruding (macroglossia)
• Short and thickened bones
• Delayed eruption of the teeth

Signs and Symptoms of Later Stages

• Retarded learning abilities
• Reduced intelligence
• Breathing difficulties
• Slow pulse
• Crying very little

Sometimes, the new born children can be of normal weight, height and without any symptoms so screening tests are done usually.

Causes of Cretinism

There are many causes by which cretinism can develop and each cause affect the production of thyroid hormones at one or the other level and includes

• Missing or misplaced thyroid gland: the thyroid gland which is responsible for the production of thyroid hormones may be absent, underdeveloped or located at a different location. It is the reason of about 85 % cases of cretinism
• Central hypothyroidism: this occurs due to some dysfunction of hypothalamus and pituitary it is due to the defects in a hormone called as TSH which is produced by the pituitary and stimulates the thyroid gland to produce thyroxine. Reduced levels of TSH hormone in blood causes less release of thyroxine hormone and the child suffers from cretinism.
• Maternal iodine deficiency: thyroid hormone is required by developing fetus and if mother is taking diet less in iodine which is essential for the production of the thyroid hormones then the baby will definitely suffer from cretinism.

Other hereditary causes: Sometimes the thyroid gland is present and still the child suffers from cretinism. It is due to the fact that that there can be problems in other proteins and enzymes which causes

• Defects in thyroid hormone synthesis and secretion
• Defects in the transport of the thyroid hormones from the thyroid gland to the different parts of the body
• Defect in the action of the thyroid hormone such that the body tissues do not respond to the hormone

Risk Factors for Cretinism

The persons with the following factors have more risk of having cretinism

• Sex: the female child has two times higher chances of suffering from cretinism than male child
• Age: according to the definition of cretinism, it is a condition which is present before or after birth. If hypothyroidism occurs in a child having age two years or older then it is not called as cretinism but called as primary hypothyroidism.
• Race: cretinism affects all types of populations but the prevalence rate is higher in Hispanic females and black infants.

Diagnosis of Cretinism

Diagnosis of the hypothyroidism can be made by measuring the levels of thyroxine and TSH hormones but some other tests can be ordered by the doctor to know the cause of hypothyroidism.   There are various tests which can be used to detect cretinism in the child as

New-born screening tests: these are the usual screening tests done by the doctor in first 24 to 72 hours of life to check for the metabolic and genetic disorders. Few drops of blood are taken as a sample from the heel by pricking it.  Three types of screening strategies are there as

• Measuring of thyroxine levels, then follow up measurement of TSH: in the usual screening test mentioned above, the level of thyroxine hormones is measured. If found below than the level of TSH is measured, for a child affected from cretinism the Thyroxine levels are low and TSH levels are high.
• Initial TSH measurement: the level of TSH hormone is measured directly without measuring the levels of thyroxine hormones
• Simultaneous measurement of both the Thyroxine and TSH hormones.

Tests to know the cause of hypothyroidism: The imaging tests like

• Thyroid radionuclide uptake and scan test can be used to check for any structural abnormalities in the thyroid gland
• Ultrasonography: the non-radioactive imaging tests to look for the structural abnormalities in the thyroid gland

Other tests can be ordered by your physician to look for the other possibilities of the cause.

Treatment of Cretinism

The overall goal of the treatment is to assure the normal growth and development of the child by restoring the levels of thyroxine hormone in the blood and a proper regular clinical evaluation. The treatment is started as early as possible as following

• Oral levothyroxine: the hormone replacement therapy includes administering l-thyroxine tablets orally. The dosage and frequency are decided by your doctor. They are given daily and throughout the life of the baby.
• Clinical evaluation: the baby should be clinically evaluated every few months during the first three years of the life. The various parameters like level of blood hormones, height, weight or normal body development are assessed
• Diet supplementation: iodine should be added in diet in iodine deficient area in the form of iodized salt. Studies shows that soy protein diet can improve the effect of levothyroxine on the baby by modulating its absorption.

Prognosis of Cretinism

Prognosis depends on the age of the baby at which the cretinism is diagnosed and treatment is initiated. If the disease is early diagnosed and the treatment is started in the first month of the life then most of the children have normal intelligence and on the other hand, new born which are not diagnosed early and treatment is started late or no treatment is started at all then these children suffer from intellectual disability, low IQ and delayed growth.

References:

• The American Association of Clinical Endocrinologists
• Endocrine society