Endocrinology

Question 1

Increased US:LS ratio

Answer 1

Suggests short lower limbs

• Skeletal dysplasias
• Hypothyroidism

Question 2

Decreased US:LS ratio

Answer 2

Suggests short trunk

• Scoliosis
• Spondylodysplasia
• Osteogenesis imperfecta
• Short neck (e.g. Klipppel Feil sequence)

Question 3

Normal US:LS ratios

Answer 3

US:LS ration

1. 7 @ birth
2. 3 @ 3 years

1 @ 8 years

0.9@ 18 years

Question 4

Normal arm span

Answer 4

• 0 - 7 years: (arm span - height) = -3cm
• 8-12 years: (arm span - height) = 0 cm
• 14 years +: (arm span - height) = +1cm girls + 4cm boys

Question 5

Polydactyly Causes

Answer 5

• Hereditary
• Carpenter syndrome (craniosynostosis, syndactyly, short stature, obesity, umbilical hernia, cryptorchidism)
• Bardet-Biedl (visual impairment, truncal obesity, hypogonadism, kidney abnormalities, learning difficulties, autosomal recessive)
• Trisomy 13

Question 6

Syndactyly Causes

Answer 6

• Smith-Lemli Opitz (autosomal recessive, short stature, microcephaly, ID, polydactyly, underdeveloped genitals, ptosis, vision problems, hypotonia, seizures, heart defects, pyloric stenosis, bowel obstruction)
• Apert (craniosynostosis, ID, hypertelorism, bulging eyes, down-slanting palpebral fissues, maxillary hypoplasia, asymmetrical face, dental problems

Question 7

Causes of short + obese

Answer 7

Endocrine

• Hypothyroid
• Hypopituitarism
• GH deficiency
• Cushing syndrome
• Pseudohypoparathyroid

Syndromal

• Prada-Willi
• Bardet Biedl
• Alstrom
• Down syndrome

Question 8

Tip for plotting mid parental height on charts

Answer 8

Girl

• Plot mums height
• Plot dads height - 13
• Midway point = mid parental height

Boy

• Plot dads height
• Plot mums height + 13
• Midway point = mid parental height

Question 9

Investigations for precocious puberty

Answer 9

• *BLOOD TESTS**
  1. Baseline LH, FSH; morning gonadal steroids: testosterone, oestradiol.
  2. GnRH stimulation test (LH and FSH responses).
  3. DHEAS (dehydroepiandrosterone sulfate), which may be extremely high in adrenal tumours.
  4. hCG (can be produced by various tumours).
  5. Thyroid function tests, including TSH level.

IMAGING
1. X-ray of left wrist and hand for bone age (the most important investigation). A
normal bone age suggests, depending on the clinical picture, premature adrenarche,
premature thelarche or ingestion of exogenous sex steroids. An accelerated bone age is more in keeping with central precocity (various causes), adrenal or ovarian pathology (such as tumour) or McC–A syndrome.

2. A skeletal survey for suspected McC–A syndrome (polyostotic fibrous dysplasia).
3. Ultrasound studies of the pelvis, testes and adrenal glands.
4. Brain MRI (for various intracranial pathologies, such as hypothalamic hamartoma,

pinealoma, hydrocephalus, third ventricular cysts).

Question 10

Precocious puberty- central causes

Answer 10

1. Central = gonadotropin-dependent = true precocious puberty (due to early activation of hypothalamic-pituitary gonadal axis). GnRH dependent.
   
   1. Idiopathic (approx. 80%) *almost all idiopathic cases are girls*
   2. Organic brain lesions
      
      1. Glioma, germ cell tumour (usually secrete hCG), hypothalamic hamartoma (also causes gelastic seizures), any insult to the hypothalamus (e.g. TS / neoplasm / hydrocephalus / trauma)
   3. Hypothyroidism prolonged an untreated
      
      1. ONLY cause of precocious puberty + SLOW GROWTH
   4. NF type 1
   5. Genetic: specific gene mutations
   6. Prolonged previous exposure to sex steroids
      
      1. McCune Albright Syndrome
      2. Poorly controlled CAH

*Main stay of treatment = GnRH agonists IM injection 3 monthly* Continues until normal age of onset of puberty

Question 11

Precocious puberty- peripheral

Answer 11

1. Peripheral = gonadotropin- independent = precocious pseudopuberty (due to excess secretion of sex hormones derived from either a) gonads b) adrenal glands or c) exogenous sources. Low or suppressed FSH / LH. High oestrogen / testosterone. GnRH stimulation test = NO increase in FSH or LH
   
   1. GIRLS
      
      1. Isosexual (feminizing) conditions
         
         1. McCune-Albright syndrome (peripheral precocious puberty + polyostic fibrous dysplasia + abnormal pigmentation-rarely crosses midline) NOT inheritable. Can also causing cushing’s syndrome + hyperthyroidism.
         2. Ovarian cysts
         3. Ovarian tumours
         4. Exogenous steroids
      2. Heterosexual (masculinizing) conditions
         
         1. Congenital adrenal hyperplasia
         2. Adrenal tumours
         3. Ovarian tumours
         4. Glucocorticoid receptor defect
         5. Exogenous androgens
   2. BOYS
      
      1. Isosexual (masculinizing) conditions
         
         1. McCune-Albright syndrome (peripheral precocious puberty + polyostic fibrous dysplasia + abnormal pigmentation-rarely crosses midline) NOT inheritable. Can also causing cushing’s syndrome + hyperthyroidism.
         2. Congenital adrenal hyperplasia
         3. Tumours
            
            1. Adrenocortical, testicular
            2. CNS, hepatoblastoma, teratoma, germ cell
            3. Mediastinal tumour: Klinefelter
         4. Familial male precocious puberty
         5. Associated with pseudohypoparathyroidism
         6. Exogenous androgen
      2. Heterosexual (feminizing) conditions
         
         1. Feminizing adrenocortical tumour
         2. Exogenous estrogens

Question 12

Anterior pituitary hormones

Answer 12

• Growth hormone
• Prolactin
• TSH
• ACTH
• LH + FSH

Question 13

Posterior pituitary hormones

Answer 13

• ADH (Vasopressin)
• Oxytocin