Cardiovascular system

• Cardiac output is reduced but peripheral vascular resistance is increased. Diastolic blood pressure may be increased and pulse pressure decreased
  
• Heart may be enlarged and pericardial effusion may occur
  
• Sinus bradycardia, low amplitude 'p' wave ST segment alterations may be obvious on the ECG
  
• Angina pectoris can occur rarely

Central Nervous system

• Deficiency in foetal / neonatal life leads to maldevelopment of CNS which is irreversible
  
• All intellectual functions are decreased. Lethargy, somnolence prevails. Headaches are frequent

Skeletal system

• Impaired linear growth occurs
  
• Joint pain and stiffness
  
• In early life if hypothyroidism occurs epiphyseal dysgenesis is known to occur

Muscular system

• Stiffness and aching of muscles
  
• Slow muscle-stretch reflexes, muscle enlargement, or atrophy

Gastrointestinal system

• Appetite is decreased
  
• Gaseous distension of abdomen
  
• Constipation
  
• Rarely ascites is present
  
• Achlorhydria and pernicious anaemia may be occasionally present

Renal system

• " Decrease in GFR (Glomerular Filtration Rate)
  " Hyponatraemia

Reproductive system

• Sexual development may be arrested or it may be precocious
  
• Decreased fertility or recurrent abortions
  
• In woman, decreased libido and anovulation are known to occur
  
• Menorrhagia, Amenorrhoea
  
• In man there is decreased libido or impotence and/or oligospermia

Skin

• Myxoedematous appearance (thickened features and puffiness) due to accumulation of mucopoly-saccharides on dermis and other tissues
  
• Non-pitting oedema, localised - around the eyes, on legs/generalised.
  
• Enlarged tongue
  
• Dry, coarse icthyotic skin
  
• Hair-dry and brittle
  
• Loss of scalp hair and/or lateral eyebrow hair
  
• Nails-brittle-break easily and grow slowly
  
• In central hypothyroidism these changes are not seen.

Haemopoietic system

• Microcytic/macrocytic anaemia can occur
  
• Capillary fragility is seen

Pituitary and adrenal

• Longstanding hypothyroidism causes increase in size of the thyroid gland
  
• Hyperprolactinaemia can be present
  
• Increased turnover of cortisol

Respiratory system

• Pleural effusion may occur in hypothyroidism, obstructive sleep apnoea is seen commonly

Ocular System

• Increased intraocular pressure

Metabolic system

• Low metabolic rate
  
• Increased lipids cholesterol, LDL cholesterol, and triglycerides