Diagnosis of congenital hypothyroidism

Detection of genetic pathologies in newborns is carried out in the first week after the birth of the baby. For the diagnosis of the condition of the newborn assessed on the Apgar scale. This system was developed by an American anaesthesiologist, where each letter APGAR defines the following indicators:

• A (appearance) - the color of the skin.
• P (puls) - pulse, heart rate.
• G (grimace) - grimaces, reflex excitability.
• A (activity) - the activity of movements, muscle tone.
• R (respiration) - the nature of breathing.

Each indicator is estimated by numbers from 0 to 2, that is, the overall result can be from 0 to 10. If congenital hypothyroidism is suspected, the most common signs of the disease are considered, and their significance is determined by such points:

• Pregnancy more than 40 weeks or prematurity - 1 point.
• Weight at birth more than 4 kg - 1 point.
• Pallor of the skin - 1 point.
• Physiological jaundice for more than 3 weeks - 1 point.
• Puffiness of the limbs and face - 2 points.
• Muscle weakness - 1 point.
• Big language - 1 point.
• Open rear fontanel - 1 point.
• Violations of the chair (flatulence, constipation) - 2 points.
• Umbilical hernia - 2 points.

If the sum of the balls is more than 5, then this is the reason for the further diagnosis of congenital anomalies, including that of the thyroid gland. It is mandatory to collect anamnestic data, an objective examination of the infant by a pediatrician, as well as a set of laboratory and instrumental examinations.

1. Objective data and anamnesis.

You can suspect the disease because of its clinical symptoms. It is the first signs of hypothyroidism due to the rare occurrence that allow for early diagnosis. When collecting the history, predisposing factors are established: heredity, a woman's illness during pregnancy and the general course of pregnancy.

2. Laboratory research.

A newborn's blood is being analyzed (heel collection) for TSH and thyroid hormone levels (neonatal screening). During pregnancy, an analysis of amniotic fluid is used by puncturing the fetal bladder with a long needle. In hypothyroidism, a reduced level of T4 and elevated TSH values are observed. A blood test for antibodies to the TSH receptor is also possible. If the concentration of TSH is greater than 50 mU / L, this indicates a problem.

3. Instrumental methods.

Ultrasound of the thyroid gland to determine the localization of the organ and the features of its development. When scanning newborns isotope 1-123 is used, which has a low radiation load. At the age of 3–4 months, the child is undergoing an X-ray of the legs to determine the true age of the skeletal system and detect thyroid hormone deficiency.

There are also special tests for determining mental development indicators (IQ). They are used to assess the condition of children older than a year and when the visual symptoms of hypothyroidism are blurred.

Screening for congenital hypothyroidism

For the early diagnosis of more than 50 genetic pathologies, all newborns are screened. A blood test is performed during the first 10 days of life. Screening for congenital thyroid disease is carried out for the following reasons:

• High incidence of congenital hypothyroidism.
• High sensitivity method.
• Most clinical signs of illness appear after three months of a child’s life.
• Early diagnosis and treatment can prevent mental retardation and other irreversible complications.

A neonatal test for thyrotropin (TSH) and thyroxin (T4) is used to detect abnormalities. Blood sampling is performed using percutaneous puncture from the heel at 4-5 days after birth in full-term babies and at 7-14 days in premature babies.

Most often screened for TSH, the possible results of tests:

• TTG less than 20 mMe / l is normal.
• TSH 20-50 mMe / l - re-examination is necessary.
• TSH above 50 mMe / L - suspected hypothyroidism.
• TSH above 50 mMe / L - emergency treatment with thyroxin is required.
• TSH over 100 mMe / L - congenital hypothyroidism.

In order for the results of the analysis to be reliable, blood is given on an empty stomach, 3-4 hours after the last feeding. The analysis is carried out 4-5 days after the start of lactation. Laboratory screening in 3-9% of cases gives false-negative results. Therefore, the diagnosis takes into account the clinical symptoms and the results of other studies.

[1], [2], [3], [4], [5], [6], [7]

Analyzes

Laboratory studies are a mandatory component of the diagnosis of various congenital abnormalities, including hypothyroidism. To identify the disease shows the following set of tests:

• General blood test for normochromic anemia.
• Biochemical analysis of blood for excessive amounts of lipoproteins and hypercholesterolemia.
• The level of free and total T3, T4.
• Determination of TSH and antibodies to its receptors.
• Antimicrosomal antibodies AMC.
• Calcitonin and other thyroid hormones.

Let us consider the main analyzes prescribed for suspected endocrine pathologies and their interpretation:

1. TSH is a hormone produced by the pituitary gland for normal thyroid function, stabilization of physiological processes in the central nervous system and metabolic processes in the body. If its performance exceeds the norm, then this indicates a violation in the body. The optimal value of TSH is 0.4-4.0 mIU / L, the results above or below this norm are a symptom of hypothyroidism.
2. T3 and T4 - amino acid thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Produced by follicular organ cells under the control of TSH. Provide biological and metabolic activity of the body. Affect the functional abilities of the central nervous system, memory, psyche, immune system.
3. Antibody testing - the immune system works in such a way that when the disease begins to produce antibodies. If the disease is autoimmune, autoantibodies are synthesized that attack the healthy tissues of the patient. In this case, the thyroid falls under the sights of one of the first.

In order for laboratory results to be reliable, it is necessary to properly prepare for testing. Blood sampling is done only on an empty stomach. Newborns take blood from the heel.

[8], [9], [10], [11], [12], [13]

Instrumental diagnostics

If hypothyroidism is suspected, the patient is prescribed a complex of various diagnostic methods, including instrumental ones. They are necessary to establish the cause that caused the disease, clarify the characteristics of the pathological process and the general condition of the body.

Instrumental diagnosis of thyroid insufficiency consists of:

• Ultrasound of the thyroid gland (study of structure, homogeneity, density).
• Ultrasound of the adrenal glands.
• CT and MRI of the head.
• ECG and vascular Doppler.
• Thyroid scintigraphy (organ function test using radioactive isotopes in the body).
• Histology and cytology of thyroid biopsy material.
• Examination of related specialists: gynecologist / urologist, neuropathologist, cardiologist.

If the pathology proceeds with a goiter, then instrumental methods reveal changes in the echo structure of the tissues of the organ: reduced echogenicity, focal changes, heterogeneous structure. Other forms of the disease have similar symptoms. In order to verify the diagnosis, in most cases, puncture biopsy is performed using a thin needle, as well as a dynamic study of TSH and comparison of the results with the symptoms of anomaly.

[14]

Differential diagnostics

The complex of tests for congenital hypothyroidism does not always allow reliable confirmation of pathology. To compare the endocrine system abnormalities with other diseases with similar symptoms, differential diagnosis is necessary.

First of all, thyroid insufficiency is differentiated with such disorders:

• Down syndrome.
• Rahith.
• Jaundice of unknown etiology.
• Birth injuries.
• Different types of anemia.

In older children, the disease is compared with:

• Physical and mental retardation.
• Pituitary Nanizm.
• Chondrodysplasia.
• Congenital dysplasia.
• Heart defects.

During the diagnosis, it is taken into account that certain diseases, such as: cardiac, renal and hepatic failure, myocardial infarction, lead to disruption of the enzyme 5-deiodinase. This entails a decrease in the level of triiodothyronine at normal T3 and T4.

Very often, hypothyroidism is mistaken for a chronic form of glomerulonephritis, since both diseases have a similar symptom complex. Also compared with circulatory failure. For differentiation, the patient is prescribed a general analysis of blood and urine, BAC studies, the level of T3 and T4, ultrasound of the thyroid gland and its radioisotope scanning.

[15], [16], [17]