Other Endocrine Disorders

Question 1

What is SIADH and what are the causes?

Answer 1

Excessive secretion of antidiuretic hormone (ADH) from the posterior pituitary gland or another source.

Causes a dilutional hyponatraemia. (low osmolality)

Causes include:

• Brain injury
• Malignancy (small cell lung cancer)
• Medications (Carbamazepine/SSRI’s/Amitriptyline)
• Infection
• Hypothyroidism

Question 2

How does SIADH present?

Answer 2

Presentation is dependent largely on the rate of change Na+ concentration.

Mild symptoms: Nausea, vomiting and headaches

Moderate symptoms:Muscle cramps, weakness and confusion

Severe symptoms include: Ataxia, seizures, reduced consciousness and coma

Question 3

How would investigate suspected SIADH and what will be seen?

Answer 3

Fluid status: patient should be euvolaemic or hypervolaemic

Na+: concentrations should be low

K+: If raised consider Addison’s

Serum osmolality: Will be low (low concentration of ions due dilution)

Urine osmolality: very high

Question 4

How do you manage SIADH?

Answer 4

If possible treat underlying cause (stop causative medicines, correct hypothyroidism)

Fluid restriction to try and increase Na+ concentration.

Can replace Na+ with IV fluids (must be careful with this as rapid changes in Na+ concentration can cause central pontine demyelination)

Question 5

What is diabetes insipidus?

Answer 5

Diabetes insipidus (DI) is a condition caused by hyposecretion of, or insensitivity to the effects of, antidiuretic hormone (ADH).

2 main types:

• Cranial: decreased secretion of ADH
• Nephrogenic: decreased ability to concentrate urine because of resistance to ADH in the kidney.

Question 6

How does diabetes insipidus present?

Answer 6

Marked polyuria, nocturia and polydipsia.

Question 7

How is diabetes insipidus investigated?

Answer 7

Fluid deprivation test with response to desmopressin.

Patient is deprived of fluids for 8 hours or for up to 5% of body weight. Urine is tested for osmolality.

Normally osmolality would be high as the urine would be concentrated in diabetes insipidus it will be dilute still and the osmolality will be low.

Desmopressin (synthetic ADH) is then administered:

• If the cause is cranial the kidneys will respond water will be reabsorbed and the urine will become concentrated (high osmolality)
• If the cause is nephrogenic the kidneys will not respond to the synthetic ADH and the osmolality will stay low.

Question 8

How do you treat diabetes insipidus?

Answer 8

In Cranial causes replace ADH with desmoperssin.

In Nephrogenic causes:

• Ensure adequate hydration to satisfy thirst to avoid dehyrdration
• Correct any electrolyte abnormalities
• High dose desmopressin may be effective
• Thiazide diuretics and NSAIDs may be beneficial in reducing UO

Question 9

What is the presentation of acromegaly?

Answer 9

Coarsening of features
Headaches
Paraesthesia
Amenorrhoea, reduced libido

Question 10

What are the main hereditary multiple endocrine neoplasia syndromes?

Answer 10

Functioning hormone tumours in multiple organs
All autosomal dominant inheritance.

MEN 1
MEN 2
Peutz-Jeghers (associated colorectal cancer) 
Von Hippel-Lindau
Neurofibromatosis

Question 11

What conditions are associated with Neurofibromatosis Type 1?

Answer 11

Neurofibroma’s all over the body

Optic glioma
Nerve sheath cell tumour
Leukaemias

Question 12

What conditions are associated with Neurofibromatosis Type 2?

Answer 12

Bilateral acoustic neuromas

Question 13

What conditions are associated with MEN 1?

Answer 13

MEN1

• Pituitary adenoma: prolactin or GH
• Parathyroid adenoma / hyperplasia
• Pancreatic tumours: gastrinoma or insulinoma

Question 14

What conditions are associated with MEN 2?

Answer 14

MEN2
-Thyroid medullary carcinoma
-Adrenal phaeochromocytoma
ƒ-Hyperthyroidism
ƒ-Marfanoid habitus