First Glance

Fundamentals

Clinical Features

The clinical features of hypothyroidism are variable, many a times nonspecific. A high index of suspicion is necessary especially in patients who are at risk for developing hypothyroidism but still are subtle in their presentation.
The clinical features vary with age of onset and severity of hypothyroidism

I Clinical manifestations of hypothyroidism in general/in adults

Fatigue
Lethargy
Mental impairment
Depression
Goitre
Non-pitting oedema
Menstrual abnormalities in women
Repeated abortions in productive age of women.

Cold intolerance
Hoarseness of voice
Dry skin
Weight gain
Arthralgias

II Hypothyroidism during adolescence

Delayed puberty
Growth retardation with delayed bone age
Galactorrhoea
Menstrual disorders in adolescent girls

III Hypothyroidism during childhood

Dry skin, generalised myxedema
Constipation
Delayed dentition
Growth retardation
Delayed skeletal maturation
Myopathy
Precocious sexual development

IV Clinical manifestations of congenital hypothyroidism

Early neonatal hypothyroidism

Prolonged icterus
Oedema
Birth weight > 4 kg
Post datism : gestation > 42 weeks
Poor feeding, hypothermia
Abdominal distension
Large posterior fontanelle

Onset during 1st month

Peripheral cyanosis/mottling
Respiratory distress
Failure to gain weight
Constipation
Decreased activity

Onset during first 3 months

Umbilical hernia
Constipation
Hoarse cry
Macroglossia
Generalised myxedema
Dry skin

End Organ Impact

Hypothyroidism can affect all systems of the body if not treated

a) 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

b) Central Nervous system

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

c) Skeletal system

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

d) Muscular system

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

e) Gastrointestinal system

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

f) Renal system

Decrease in GFR (Glomerular Filtration Rate)
Hyponatraemia

g) 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

h) 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.

i) Haemopoietic system

Microcytic/macrocytic anaemia can occur
Capillary fragility is seen

j) Pituitary and adrenal

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

k) Respiratory system

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

l) Ocular System

Increased intraocular pressure

m) Metabolic system

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

In the following section we will discuss the comorbidity associated with hypothyroidism

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