What is cretinism ?

Cretinism is a condition produced due to hypothyroidism since birth due to partial or complete failure of thyroid gland  (commonly it is due to thyroidal agensis).

Juvenile myxoedema is a condition with onset of hypothyroidism since childhood but develops before puberty ,this is only due to dyshormonogenesis

Myxoedema is characteried by onset of hypothyroidism after puberty (probably Hashimolo's thyroiditis is the commonest cause of myxoedema).

What are the morphologic characteristics of cretin?

 The facies in cretinism 

• Appearance is dull and idiotic.
• There is depressed bridge of the nose, broad flat nose with big nostrils.
• Hypertelorism (widely set eyes) with wrinkling of eyebrows : narrow palpebral fissures.
• Cretin has Sparse hair with dry skin.
• Their lips are thick and everted with big, protruded tongue (macroglossia)
• There is Delayed dentition.

The other features are

• Short stature but they maintains the infantile proportion, ie. upper segment > lower segment.
• These patients are lethargic and apathetic.
• Memory is grossly impaired. Markedly retarded intelligence
• Skin is dry. rough  and cold with sparse scalp hair.
• Thick and short neck with presence of supraclavicular pad ot fat.
• Pot-bellied abdomen with umbilical hernia is observed

Clinical features of hypothyroidism in neonatal period

Hypothyroididm in the neonatal period may be associated with the following

• Prolonged physiological jaundice.
• Somnolence.
• Feeding problem (difficulty in sucking)
• Constipation
• Hoarse cry 
• Delayed milestones of development (is observed in  later months)

How will you diagnose cretinism based on laboratory tests?

Blood investigations

• High serum cholesterol.
• Low protein bound iodine
• Low radioactive I131 uptake.
• T3 and T4 levels are low with high TSH level.

ECG - Low voltage complex is seen.

Skeletal x-ray (of long bones and pelvis) 

In cretinism there is delayed closure of epiphysis (i.e. bone age is less than that of chronological age).

Epiphyseal dysgenesis - Instead of one epiphysis, there are multiple epiphysis (This is DIAGNOSTIC of cretinism).

How will you treat Cretin?

• Very small dosage of L-thyroxine is needed. Initial dose is 10 to 25 microgram and the dose is adjusted according to clinical improvement as well as the biochemical findings.
• Rehabilitation.

What are the cardinal features of achondroplasia ?

Dwarfism in achondroplasia is due to decrease in the proliferation of cartilage present in growth

plate.This  is an autosomal dominant disease and is usually recognised at birth. The dwarf jokers we see in the circus are usually achondroplasia patients. 

The characteristics features are 

• Dwarfism.
• Normal mental and sexual development.
• Short limbs.
• Large head with saddle nose.
• Lumbar lordosis: kyphoscoliosis.

What is pseudohypoparathyroidism ?

Pseudohypoparathyroidism  is a condition with increased  secretion of parathormone (PTH) is there but due to end organ resistance, there is no response to PTH hormone resulting in clinical features of hypoparathyroidism. This is a hereditary disorder with distinctive skeletal and developmental defects. These patients have elevated levels of serum PTH.

The common features are :

• Short height with stocky built.
• Round face with short neck.
• Mental retardation.
• Epileptic convulsions.
• Short 4th and 5th metacarpals and metatarsals.
• Basal ganglia calcification.

How will you differentiate dwarfism by body ratio?

Based on upper and lower segment ratio dwarfism is classified as follows
Upper segment = Lower segment is seen in 

• Hereditary.
• Constitutional
• Pituitary dwarf.

Upper segment > Lower segment is seen in 

• Achondroplasia.
• Cretinism
• Juvenile myxoedema.

Upper segment < Lower segment is seen in 

• Spinal deformities

You should always remember that short stature may be associated with features of delayed puberty.

Dwarfism and its causes

Dwarfism is defined as marked permanent shortness of stature, with predicted adult height of the person less than 4 standard deviations from the mean. An adult may be called a dwarf, if his height is less than 4 feet.

What are the causes of short stature?

Normal variant of short stature

• Familial short stature
• Constitutional growth delay
• Racial.

Pathological causes of short stature

Proportionate dwarfism

• Prenatal
• Intrauterine growth retardation 
• Antenatal infection in mother (TORCH*,syphilis, AIDS)
• Antenatal consumption of alcohol, tobacco, heroin
• Chromosomal disorders (Down's syndrome, Turner's syndrome). 
• Postnatal
• Malnutrition ,Protein-energy malnutrition, anorexia nervosa
• Endocrine disorder growth hormone deficiency, hypothyroidism, congenital adrenal hyperplasia, precocious puberty pseudohypoparathyroidism
• Cardiovascular disorders of cyanotic and acyanotic congenital heart disease, early onset rheumatic heart disease.
• Respiratory disorders Kartagener's syndrome, cystic lung disease, childhood asthma 
• Renal disorders renal tubular acidosis, renal rickets, nephrotic syndrome, chronic' pyelonephritis
• Blood disorders ,chronic anemia like thalassemia or sickle cell anemia leukemia
• Psychosocial disorders (maternal deprivation)

Disproportionate dwarfism

• Rickets 
• Skeletal dysplasia (kyphosis, lordosis, scoliosis)
• Defective bone formation (osteopetrosis, osteogenesis imperfecta)
• Defective cartilage growth (achondroplasia multiple cartilagenous exostosis)
• Defective bone matrix (fibrous dysplasia)
• Inborn error of metabolism (mucopolysaccharidosis)
• Calcium and phosphorus metabolism defects (hyperphosphatemic rickets)
• Metabolic disease (Wilson's disease, zinc deficiency).

What are the common causes of shortstature?

• Hereditory
• Constitutiona; delay in growth
• Protein energy malnutrition (this is the commonest cause of malnutrition in developing countries)
• Rickets.
• Cretinism.
• Pituitary dwarf.
• Achondroplasia: mucopolysaccharidosis
• Congenital cyanotic heart diseases e.g. Fallot s tetralogy
• Gross kyphoscoliosis
• Down’s syndrome or Turner's syndrome.