Define Iodine Deficiency Disorders. Describe its types, management and prevention.

Definition

• Iodine Deficiency Disorders (IDD) comprise the spectrum of consequences of iodine deficiency.
• Iodine is essential for synthesis of thyroid hormones (T3 & T4), which are critical for growth and brain development.
• IDD is the commonest preventable cause of intellectual disability worldwide.

Spectrum of Idd

• Fetus: abortion, stillbirth, congenital anomalies, increased perinatal mortality.
• Neonate / child: neonatal & juvenile hypothyroidism, goitre, impaired growth and mental development.
• Endemic cretinism — the most severe form.

Endemic Cretinism (2 Types)

• Neurological cretinism — intellectual disability, deaf-mutism, squint, spastic diplegia (euthyroid).
• Myxoedematous cretinism — dwarfism, coarse features and hypothyroid signs.

Goitre

Diffuse or nodular thyroid enlargement due to compensatory TSH-driven hyperplasia; graded by WHO (Grade 0 → Grade 2, visibly enlarged).

Assessment (community Indicators)

• Total goitre rate; urinary iodine excretion (the best population indicator; median < 100 µg/L = deficiency).
• Neonatal TSH screening; monitoring of salt iodine content.

Management

• Correct iodine deficiency (iodised salt / iodised oil) and treat associated hypothyroidism with levothyroxine.
• Endemic cretinism is largely irreversible — hence prevention (especially antenatal) is paramount.

Prevention & Control

• Universal Salt Iodisation — the main strategy (iodised salt should contain ≥ 15 ppm iodine at the consumer level).
• Iodised oil (oral/injectable) in severely endemic areas; implemented under the National IDD Control Programme (NIDDCP).

At-risk Populations

• Populations in hilly / sub-Himalayan and iodine-poor soil areas (endemic goitre belts).
• Pregnant & lactating women and young children (highest requirement and greatest harm from deficiency).

Iodine deficiency is the commonest preventable cause of mental retardation.