Cretinism

Introduction

Let us learn the concept of cretinism. Cretinism is a medical condition that affects physical and mental growth. Cretinism is caused by the lack of thyroid hormone, which is usually due to a low intake of dietary iodine. Cretinism symptoms include stunted growth, weariness, malnutrition, thickened facial features, abnormal bone growth, mental retardation etc. Cretinism types can be divided into neurological cretinism and Myxoedematous or hypothyroid cretinism. Mental retardation, deaf-mutism, squint, spastic diplegia, posture and gait problems are all symptoms of neurological cretinism. Cognitive impairment, dwarfism and hypothyroidism with concomitant somatic symptoms characterise myxoedematous or hypothyroid cretinism. Pediatric endocrinologists treat congenital hypothyroidism. The basic therapy included the provision of thyroid hormone to the infant (levothyroxine). There are various ways to diagnose cretinism, including a prenatal screening test, test for radioactive iodine (RAIU) etc. The World Health Organization (WHO) has now identified iodine deficiency as the most frequent cause of brain injury, with over 2 billion people in 130 countries at risk.

Cretinism: Meaning and Definition

Cretinism is also known as Congenital iodine-deficiency syndrome. Congenital hypothyroidism is when the thyroid gland is underactive at birth, causing growth retardation, developmental delays and other abnormalities. Cretinism can be caused by a lack of iodine in the mother’s diet when she is pregnant. Iodine is required by a baby’s body to produce thyroid hormones. These hormones are necessary for the proper development of the brain and neurological system and healthy growth. Thyroid hormone synthesis problems affect roughly 15% of patients with congenital hypothyroidism in the industrialized world and these people frequently have a goiter. The transplacental transfer of maternal blocking antibodies from women with autoimmune thyroiditis is responsible for a tiny percentage of instances. However, most cases are caused by thyroid dysgenesis, which includes ectopic/hypoplastic, hypoplastic or missing glands (agenesis).

Thyroid hormones are required to develop and grow a wide range of target tissues, including the brain and skeleton. Thyroid hormone has a limited effect on essential genes for neurodevelopment and even a brief period of thyroid hormone shortage can result in irreparable brain damage. The development of the fetal brain during the first trimester of pregnancy depends entirely on the mother’s thyroid function.

Types of Cretinism

1. Neurological Cretinism

In its fully evolved form, the extremely severe mental deficit, squint, deaf-mutism, spastic diplegia and stance and gait problems are the three hallmarks of endemic neurological cretinism. Usually, they have a goiter. Underdevelopment of the cochlea for deafness, maldevelopment of the cerebral neocortex for mental retardation and maldevelopment of the corpus striatum (particularly putamen and globus pallidus) for motor dysfunction are all neuropathological causes of the clinical presentation. The cerebellum, hypothalamus, visual system and hippocampus are mostly unaffected. Maternal hypothyroidism owing to iodine insufficiency is now the primary etiology of neurological cretinism. It’s also possible that it’s autosomal recessive.

2. Myxedematous Cretinism

Mental retardation (though less severe than in neurological cretinism), severe growth retardation (dwarfism), incomplete maturation of countenance, including the naso-orbital configuration, atrophy of the mandibles, puffy features (myxedema) and hypothyroidism with associated physical symptoms can all occur in myxedematous cretinism (e.g. thickened and dry skin, dry and decreased hair, eyelashes and eyebrows, husky voice and far delayed sexual maturation). Thyroid atrophy is indicated by the absence of goiter and the inability to palpate the thyroid. Thyroid radioiodine uptake is significantly lower than in the overall population. T4 and T3 levels in the blood are exceedingly common, frequently undetectable, while TSH levels are excessively high. 

Causes of Cretinism

Dietary iodine deficiency or hyposecretion of thyroxine hormone are the most prevalent causes of congenital hypothyroidism worldwide. Iodine is a trace element required for the production of thyroid hormones. Iodine deficiency is the most pervasive avoidable cause of brain injury in newborns and children worldwide. Although iodine is present in many foods, it is not sufficient in all soils.

The following factors can induce congenital hypothyroidism in newborns;

• A thyroid gland that is absent, poorly developed or unusually tiny
• Thyroid hormone production is affected by a genetic abnormality
• During pregnancy, the mother’s diet contains insufficient iodine
• Thyroid cancer therapy with radioactive iodine or antithyroid medication during pregnancy
• Antithyroid drugs, sulfonamides or lithium during pregnancy can affect thyroid hormone production

It is still the most prevalent avoidable cause of poor neurological function globally, even after the arrival of iodised salt. We must obtain iodine from food since our bodies do not produce it. Iodine enters food via the soil. As a result, iodine deficiency exists in several places of the world.

Symptoms of Cretinism

• Stunted growth and mental impairment are common symptoms
• Small stature (dwarfism)
• Mild neurological impairment with a loss of coordination and muscular tone
• Defects in hearing and speaking
• With the typical walking technique, unable to maintain posture and balance
• Myxoedema
• Thyroid gland enlargement is when the thyroid gland becomes larger (goiter)
• Hair and nails that are scant
• The voice will be harsh and deep
• Sexual characteristics are hampered
• Skin that has thickened
• Tongue enlargement
• Abdomen protrudes
• An umbilical hernia is a kind of hernia that occurs when the umbilical
• Tendon reflexes are delayed
• The Intelligent quotient has dropped (IQ)

Diagnosis

Cretinism can be diagnosed with the help of:

• A prenatal screening test can detect congenital cretinism with severe hypothyroidism in the first month of life
• Thyroid scan with technetium (Tc– 99m pertechnetate)
• Test for radioactive iodine (RAIU) (to differentiate between congenital absence and defects in the organification process)
• Guthrie’s test is a postnatal blood spot test
• Thyroid binding globulin (TBG) and TSH levels in the blood are elevated
• T3 levels in the blood are high, whereas T4 levels are low

Treatment

Congenital iodine deficiency has been nearly eradicated in affluent nations thanks to food iodine supplementation and newborn screening with a blood test for thyroid function.

Thyroxine is given to the patient for the rest of their lives (T4). Even for neonates, thyroxine must be dosed as tablets alone, as liquid oral suspensions and compounded forms cannot be used for accurate dosage. T4 pills are broken and blended with breast milk, formula milk or water for newborns. Larger dosages may be necessary if the drug is taken with formulas containing iron or soya products, as these ingredients may interfere with thyroid hormone absorption from the intestines. To verify that afflicted newborns are within the normal range, TSH blood levels should be checked every 2–3 weeks throughout the first few months of life.

Prevention

Universal salt iodisation is the key option for eradicating iodine deficiency in pregnancy in virtually all countries. However, ubiquitous salt iodisation may not always be practical, resulting in insufficient iodised salt access for women of reproductive age and pregnant women. Supplementing these individuals with iodine should be explored. Countries should examine their salt iodisation programs and then decide if supplementation is necessary, according to WHO/UNICEF/ICCIDD. Highly populous nations should use disaggregated data and divide the country into subnational (region, province, district, and, so on) categories. To guarantee a sufficient iodine supply during pregnancy, women should be given an appropriate iodine intake (150 g/day) for a lengthy period before conception to establish substantial intrathyroidal iodine storage. Because the iodine demand of a woman who is actively nursing her kid is likely much higher than during pregnancy, a sufficient iodine supply should remain after parturition.

Conclusion

Cretinism is caused by the lack of thyroid hormone, which is usually due to a low intake of dietary iodine.Dietary iodine deficiency or hyposecretion of thyroxine hormone are the most prevalent causes of congenital hypothyroidism worldwide. Iodine is a trace element required for the production of thyroid hormones. Here we have covered the basic concepts of cretinism, definition and cretinism examples.