hypothyroidism and screening and management pptx

a medical presentation about hypothyrodism

1. H ypothyroidism

2. Thyroid gland is present in the middle of the neck wrapping around the cricoid cartilage and superior tracheal rings. It extends from C5 to T1vertebrae. It is a butterfly shape endocrinal gland composed of 2 lobes connected at the midline with isthmus.

3. Functions of thyroid hormone: 1. Metabolic a. Thyroid hormones stimulate metabolic activities in most tissues, leading to an increase in basal metabolic rate with increased heat production. b. Carbohydrate: thyroid hormones are diabetogenic (↑ glucose absorption from GIT and ↑ gluconeogenesis and glycoenolysis ). c. Protein: thyroid hormones promote growth in children (anabolic). In large doses, they are catabolic.

4. d . Fat metabolism: they enhance oxidation of fatty acids in many tissues. Plasma concentrations of cholesterol and triglycerides are inversely correlated with thyroid hormone levels. e. Vitamins: they increase vitamin B12 absorption and help in conversion of carotene to vitamin A in intestinal mucosa.

5. Bone: Thyroid hormones affect the rate of bone replacement. Too much thyroid hormones in body speeds the rate at which bone is lost. If they stay too high for a long period, there is a higher risk of developing osteoporosis. 3 . Bone marrow: they stimulate erythropoiesis.

6. 4. CVS: a. They increase the action of catecholamines leads to ↑ HR, ↑ COP and ↑ SBP. b. They lead to peripheral vasodilation leads to ↓ DBP. 5. GIT: they increase GIT motility. 6. CNS: a. They increase muscle tone and reflexes. b. Normal levels of thyroid hormone are essential to the development of the fetal and neonatal brain. 7. Reproductive system: they regulate menses. Normal reproductive physiology is dependent on having essentially normal levels of thyroid hormones.

7. CONGENITAL HYPOTHYROIDISM

8. Definition • Congenital hypothyroidism (CHT) is a condition resulting from an absent or underdeveloped thyroid gland ( dysgenesis ), or gland developed but cannot make thyroid hormone because of a ‘production line’ problem ( dyshormonogenesis ). • Babies with CHT cannot produce enough thyroid hormone for the body’s needs. • The term ‘congenital’ means that the condition is present at birth.

9. Causes congenital hypothyroidism: Primary hypothyroidism : 1 . Defect of fetal thyroid development ( dysgenesis ) • Aplasia • Hypoplasia • Ectopia 2 . Defect in thyroid hormone synthesis ( dyshormonogenesis )

10. 3. TSH unresponsiveness 4. Resistance to thyroid hormone. 5. Maternal antibodies: thyrotropin receptor–blocking antibody: ( TRBAb , measured as thyrotropin -binding inhibitor immunoglobulin). 6. Iodine deficiency (endemic goiter). 7. Maternal medications : Propylthiouracil , methimazole • Radioiodine

11. Central hypothyroidism: • Isolated TSH deficiency. • Isolated TRH deficiency: mutation in TRH gene. • TRH unresponsiveness: mutation in TRH receptor gene. • Multiple congenital pituitary hormone deficiencies.

12. Symptoms of congenital hypothyroidism: • Most of affected infants are asymptomatic at birth & hence the importance of neonatal screening for hypothyroidm . Symptoms develop weeks or months after birth . • In severe cases, the early signs of congenital hypothyroidism Include: Birth weight may be ↑

13. hypotonic and abdominal distension Hypothermia Constipation Umbilical hernia Mottling of skin ± cold dry skin Lethargy, sluggishness & poor feeding Wide anterior fontanel Prolonged physiological jaundice Opened, large posterior fontanel

14. • Presentation of untreated hypothyroidism during infancy and childhood (neglected hypothyroidism) : By 3-6 mo of age the clinical picture is fully developed. Retardation of physical and mental development. Learning difficulties The child’s growth will be stunted, the extremities are short, and head size is normal or even increased. The anterior fontanel is large and the posterior fontanel may remain open. The eyes appear far apart, and the bridge of the broad nose is depressed.

15. The palpebral fissures are narrow and the eyelids are swollen. The mouth is kept open, and the thick, broad tongue protrudes. Dentition will be delayed. The neck is short and thick, and there may be deposits of fat above the clavicles, and between the neck and shoulders. The hands are broad and the fingers are short. The skin is dry and scaly. Myxoedema is manifested, particularly in the skin of the eyelids, the back of the hands, and the external genitals. The hair is coarse, brittle, and scanty.

16. NEONATAL SCREENING

17. How are babies screened for hypothyroidism? All babies have a heel-prick blood test at seventh day of age to screen for several conditions. One of these conditions is CHT and this is tested for by measuring a hormone called TSH (thyroid stimulating hormone). § TSH is produced by the brain and is a messenger to tell the thyroid gland to make more thyroid hormone.

18. If the thyroid hormone is low, the brain makes more TSH message to tell the thyroid to work even harder. § If the TSH is high on the heel-prick blood test, it suggests that the thyroid hormone is low and the baby will need to have a small blood sample taken from a vein to confirm the diagnosis. § This is very successful to diagnose more than 95% of cases if a high TSH (>20 uIU /ml) and/or low T4 (< 6.5 ug /dl) are detected.

19. Newborn screening § Newborn bloodspot screening (NBS) is an important public health program that facilitates the early identification and management of babies at risk of having rare but serious medical conditions that can affect normal development. Currently , conditions that can be identified through newborn bloodspot screening include phenylketonuria (PKU), congenital hypothyroidism, cystic fibrosis (CF) and approximately 22 other metabolic conditions that affect fat or protein metabolism.

20. Screening is conducted using a small blood sample obtained by pricking the baby’s heel, 48–72 hours after birth. This sample is collected onto an absorbent paper card and is processed at the Newborn Bloodspot Screening Laboratory.

21. Treatment of congenital hypothyroidism: levothyroxine (synthetic thyroid hormone, T4) should be started without delay. § The dose is carefully calculated based on the weight of the baby, and will need adjusting regularly as the baby grows. The adjustment is monitored by blood tests that measure thyroid hormone and TSH levels.