CRETINISM

CRETINISM:

Introduction:

·         A congenital disease due to abesence or deficiency of normal thyroid secretion, characterized by physical deformity, dwarfism and mental retardation and often by goitre.

·         In Cretinism arrested physical and mental development with dystrophy of bones and soft tissues due to congenital lack of thyroid gland secretion from hypo-function or absence of gland.

·         Cretinism is a medical condition present at birth wherein there is decreased or absent thyroid function and thyroid hormone production, when untreated this condition lead to severely stunted physical and mental growth of the newborn. This is also known as Congenital Hypothyroidism.

                                          

Definition:

Cretinism term refers to severe hypothyroidism during birth deficiency of thyroid hormone leading to stunted physical and mental growth.

Types of Cretinism:

Cretinism is classified into following types:

a)      Endemic Cretinism:

It has the highest prevalence and arises due to insufficient dietary iodine intake it is common in areas with iodine deficient soils. This form is regarded as a major public health problem in many countries.

b)      Neurological Cretinism:

It is caused by thyroid deficiency in maths driving the first and second trimesters of pregnancy. This leads to foetal iodine deficiency and consequent thyroid insufficiency, leading to neurological problems like inability to hear and perform motor function and brain damage.

c)       Myxedamatous Cretinism:

Mental detainment is less severe in this form than in the neurological cretinism. It is marked by a number of abnormal effects, such as myxedematous (dry) skin, infrequent hair and a protruding abdomen.

Causes of Cretinism:

Most cases of cretinism has caused by genetic mutation. These involve anomalies in the production of enzymes that are needed for the thyroid hormone synthesis. Here are some underlying causes of cretinism:

a)      Hereditary in origin:

A small percentage of cretinism patients have inherited anomalous genes that cause the thyroid gland to produce less thyroid hormone.

b)      Missing or misplace thyroid gland:

·         Most babies born with cretinism have either no thyroid gland or gland is underdeveloped wherein in other the thyroid gland can be found on a different location such as under the tongue or side of the neck. Normally, the thyroid gland is at centre and front of the neck and near at the top of the windpipe. In some patients with cretinism thyroid gland is smaller than the normal size.

·         If there are abnormalities like the thyroid gland is thin in size or either less or no thyroid hormone will be produced. This kind of defect is not inherited.

c)       Maternal thyroid condition and medications:

·         There are cases wherein the mother of the foetus is diagnosed with thyroid problems.

·         The treatment which involves snit- thyroid glands also contribute to the occurrence of cretinism.

d)      Dysfunction of the pituitary gland or Hypothalamus:

·         Thyroid gland is not stimulated by the pituitary gland due to the dysfunction of the pituitary gland.

·         It occurs in 5% of the cretinism patients.

·         Hypothalamic causes of the cretinism include ischemic damage, congenital defects and tumours.

Symptoms of Cretinism:

Newborn screening test is usually done by the doctors to detect the presence of cretinism or Congenital hypothyroidism. This is utilized since most newborns shows mild or no symptoms at birth. Some of the symptoms are listed below as follows:

Ø  Excessive sleeping

Ø  Decreased activity

Ø  Poor feeding pattern

Ø  Constipation: Less frequent bowel movement

Ø  Choking

                                      

Signs of Cretinism:

Ø  Low hair line

Ø  Face: The newborn’s face looks dull, puffy and have slow reaction

Ø  Macroglossia: Large tongue, thick and protruding

Ø  Protruded belly bottom

Ø  Edema: Periorbital (eyelids), extremities, genitalia

Ø  Juandice: Yellowish discolouration of the skin

Ø  Hypothermia: low temperature

Ø  Hypotonia: Decreased muscle tone, “floppy baby”

Ø  Hoarse or low cry

Ø  Dyspnea: Difficulty in breathing

Ø  Cardiac problems: Bradycardia (slow pulse), heart valve abnormality

Ø  Short stature or poor growth

Ø  Poor weight gain

 

Diagnosis of Cretinism:

1)      Newborn screening test:

·         This is a screening test which is used to detect the newborn for metabolic and genetic disorders. The sample is collected by obtaining a few drops of blood using the heel- prick method.

·         This is done to detect the possible occurrence of these disorders to prevent physical disabilities, mental retardation and death.

·         This test is usually done in the first 24- 72 hrs of life.

2)      Measurement of TSH or thyroxine (T4):

·         The sample is obtained on the second and third day of life.

·         High levels of TSH and low levels of T4 confirm the congenital hypothyroidism or cretinism.

·         When this is the result of the test, the parents of the newborn are referred to a paediatric endocrinologist. This is for the confirmation of diagnosis and initiation of the treatment.

3)      Imaging studies:

·         This is recommended by the doctors to examine is there is the presence of structure abnormalities of the thyroid gland. This procedure will aid in the differentiation, if the cause is congenital absence or Organification defect.  Organification is the process needed to facilitate thyroid hormone production.

4)      X- rays: Usually the X-rays of the baby’s legs are used for this study. This is to show the bone ends at the knee joints. Also from the X- rays images, the doctor can see if there are immature appearances in babies with hypothyroidism. Lastly, it aids in the  diagnosis confirmation.

Treatment of Cretinism:

The main goal of the treatment is early detection and early initiation of the treatment. When the diagnosis is made early within the 1-2 weeks of life, the effects of this condition to the brain and nervous system can be prevented by the thyroid hormone replacement. This is due to the fact that they are not well developed. Some of the treatments are listed below:

a.       L-Thyroxine:

·         The thyroid hormone replacement involves the administration of L- thyroxine. This is a synthetic thyroid hormone which comes in tablet form. The amount and frequency of this indication is determined by the doctor and endocrinologist. As the child grows up the dose is gradually increased. This is to be given to the baby throughout his life.

·         L- thyroxine is in the form of small tablets. They are crushed an added into the milk formula of the baby.

·         This is also given 30 minutes prior to feeding.

b.      Monitoring and Evaluation:

·         Regular visits to the doctor are essential to examine the child’s weight, height, development and general health. Also, it is expected that the child will be having regular blood tests every 1-3 months until one of age. This is performed to detect the thyroid hormone levels. Then the frequency of blood tests decrease as the child reaches age 3.

            

·         Mental development monitoring: This includes four areas to be evaluated. These are communication and personality behaviour; motor ability, adaptive behaviour and language ability.

·         Growth development evaluation: Formal evaluation of the child’s development growth is monitored continuously to provide early intervention programmes. If the child shows any delays in areas of learning or speech, these programmes can be arranged to provide help to the child before school age.

c.       Diet:

·         Dietary iodide supplementation: This is particularly useful for people who are in iodine deficient areas. Dietary iodine contributes to the prevention of brain damage in cretinism endemic areas.

·         Soy based formulas and iron medication: These can reduce the absorption of the synthetic L- thyroxine being given to the baby.

d.      Activity:  This should be encouraged in children with cretinism. This is to help them in developing their motor skills.

Prognosis of Cretinism:

Early diagnosis of the disease leads to better prognosis. The newborns that are diagnosed and treated within their first months of life usually have normal intelligence. On the other hand newborns, which are not treated immediately or not treated at all suffer from intellectual disability and delayed growth. According to some studies, some of the patients with cretinism have been found to have slight decreased performance in their IQ as well as in verbal and math. They have memory and attentive deficits due to delayed diagnosis and treatment.

Prevention of Cretinism:

As endemic cretinism arises from a dietary iodine deficiency, iodine administration has been established as a health policy in many countries. Screening of newborns can help to detect the disorder in the first trimester of pregnancy. Adequate dietary iodine intake by pregnant mother can also prevent cretinism in infants.

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