HYPOTHYROIDISM

Dr.venkat

DNB Family medicine

ANATOMY

HISTOLOGY

MECHANISM OF ACTION

REGULATION OF SYNTHESIS

FUNCTIONS Carbohydrate metabolism Cholesterol metabolism Growth Skeletal muscle Heart CNS Calorigenic action

Reproductive system Hepatic conversion of carotene to

vitamin A

CLINICAL MANIFESTATIONS SKIN Cool and pale Sweating is decreased Yellowish tinge Hyperpigmentation Coarse hair Hairloss Non pitting edema Cold intolerance

EYES Periorbital edema

Graves opthalmopathy

HEMATOLOGIC Normocytic anemia

Microcytic anemia

Macrocytic anemia

CARDIOVASCULAR

Decreased heart rate Decreased cardiac output Pericardial effusion Diastolic hypertension Hypercholesterolemia hyperhomocystinemia

RESPIRATORY

Fatigue Shortness of breath on exertion Hypoventilation Sleep apnea Hoarseness of voice

GASTROINTESTINAL

Constipation Ascites Weight gain Gastric atrophy Celiac disease is more common

REPRODUCTIVE

Oligorrhea Amenorrhea Menorrhagia Decreased fertility Early abortion

NEUROLOGIC

Mental slowing

Myxedema coma

Mental retardation

MUSCULOSKELETAL

Joint pains

Aches

stiffness

METABOLIC

Hyponatremia

Hyperlipidemia

Increased homocystine

NORMAL VALUES TSH 0.4- 5.0 mU/L

Total T4 4.6-11.2 mcg/dl

Total T3 75-195 ng/dl

Free T4 0.8-1.8 ng/dl

Free T3 2.3-4.2 pg/ml

INITIAL DOSE Young healthy-1.6mcg/Kg wt Elderly-50mcg H/O coronary artery disease-25mcg TIMING OF DOSE Half an hour before food SIDE EFFECTS-Rare Allergy to dye in the tablets

MONITORING Every 6 weeks If TSH is not with in normal range

increase the dose by 12.5-25mcg If TSH normal ,monitor TSH once a year

SECONDARY HYPOTHYROIDISM Thyroid replacement and monitor free

T4 and not TSH levels. Look for other hormone deficiencies

before starting T4.

HYPOTHYROIDISM DURING PREGNANCY Normal TSH values in pregnancy First trimester 0.1-2.5

Second trimester 0.2-3.0

Third trimester 0.3-3.0

PREGNANCY COMPLICATIONS Preclampsia Placental abruption Gestational hypertension Preterm delivery Postpartum hemorrhage Low birth weight

DIAGNOSIS AND MANAGEMENT

Diagnosis is based on TSH and free T4 result

Moderate to severe 1.6mcg/kg wt

TSH <10 1 mcg/kg wt

Monitor TSH every 4 weeks

POST PREGNANCY TSH values between 2.5-4.5 during

pregnancy stop treatment Pre existing hypothyroidism-pre

pregnant dose to be continued