19. Diseases of the pituitary Flashcards
What are the three most common hormone producing adenomas of the anterior pituitary?
Prolactin, GH, and ACTH.
What is the most common type of pituitary adenoma?
Prolactinoma.
What is the limit for micro and macroadenomas?
1cm
What are the consequences of micro and macroadenomas?
- Hormone overproduction
- Mass effects : visual field disturbance, hormone deficiencies, increased prolactin, intracranial hypertension, and neurological complications.
What are the five most common types of pituitary adenomas?
- Prolactinoma,
- Hormonally inactive (including gonadotropin secretion without clinical consequences),
- GH,
- PRL + GH,
- Cushing-disease.
What are the common hormonal examinations for screening pituitary adenomas?
- Prolactin,
- cortisol, ACTH,
- TSH, fT4,
- IGF-1,
- LH, FSH, and sexual steroids.
What are the typical symptoms of prolactinoma in women?
- Galactorrhea,
- amenorrhea
- osteoporosis
- mass effects (visual field, hormone deficiency)
What are the typical symptoms of prolactinoma in men?
- Loss of libido,
- impotence,
- osteoporosis
- mass effects (visual field, hormone deficiency)
(but less visible symptoms than in women)
What are the drug causes of hyperprolactinemia?
- Dopamine-antagonist drugs (D2-receptor antagonists),
- antipsychotic drugs (e.g., risperidone),
- antidepressants,
- antiemetic drugs (e.g., metoclopramide),
- antihypertensive drugs (e.g., verapamil, methyldopa).
What is the therapy for prolactinoma?
- Drug therapy : dopamine agonists (cabergolin),
- surgery if threatening visual field loss or neurological consequences
- irradiation therapy
What are the symptoms of acromegaly?
- Growth of the hands, feet, nose, tongue, ears, lips, carpal tunnel syndrome (!!)
- visceromegaly (cardiomegaly),
- increased colon tumor prevalence,
- sweating and oily skin (!!)
- diabetes mellitus
- endocrine disorders (impotence, amenorrhea)
What is the most common cause of death in acromegaly patients?
Cardiovascular (heart insufficiency) is the most common cause of death
What is the laboratory screening test for acromegaly?
Serum IGF-1.
What is the confirmation test for acromegaly?
- OGTT (Oral glucose tolerance test) with 75 g glucose per os,
- blood taking at 0, T+30, T+60, T+ 90, T+120, T+180
What is the normal GH level during an OGTT?
Normally GH goes below 1 ng/ml, but in the case of acromegaly, it does not go below 2 ng/ml, and often a paradoxical increase of GH is observed.
What are the three types of drug therapy for acromegaly?
- Somatostatin Analogues (Octreotide, Lanreotide, Pasireotide),
- GH-Receptor Antagonist, Pegvisomant (Somavert),
- Dopamine Agonists (Cabergolin).
What are non-drug treatment options for acromegaly?
Surgery and irradiation.
What is the order of the loss of anterior lobe hormones in hypopituitarism?
The order of the loss of anterior lobe hormones in hypopituitarism is
1. GH,
2. LH/FSH,
3. TSH,
4. ACTH.
What are the causes of hypopituitarism?
- neoplastic : tumors
- traumatic (operation, trauma, irradiation),
- congenital (e.g. Prader-Willi sy),
- inflammatory : autoimmune hypophysitis, Syphilis, Meningoencephalitis,
- infiltrative : Sarcoidosis,
- vascular : postpartal necrosis, stroke
- drug induced (long steroid therapy)
What is Sheehan syndrome?
Sheehan syndrome occurs when the anterior pituitary gland is damaged due to significant blood loss. Classically, this happens after delivery
What are some symptoms of hypopituitarism?
- Weight loss, fatigue, fine wrinkles on the face, and hypotension
- Secondary hypogonadism / hypothyroidism / adrenal insufficiency
Why is there no aldosterone deficiency in hypopituitarism?
Because part of it is controlled by RAAS, which is enough to compensate
What is the difference in LH and FSH levels between primary and secondary hypogonadism?
In primary hypogonadism, LH and FSH levels are high, while in secondary hypogonadism, LH and FSH levels are low.
What is the hormonal diagnosis for GH-deficiency?
- Low IGF-1 levels
- Low LH, FSH
- Low TSH, ft4
- Low ACTH and cortisol
How can we exclude adrenal insufficiency when we see low ACTH?
if cortisol is above 20ug/dl in the morning, adrenal insufficiency can be excluded
How is the Insulin-Hypoglycemia Test performed?
- Give rapid acting insulin to provoke ACTH and GH
- Blood taken every 15 Min. after insulin and during hypoglycemia (blood sugar <2.2 mmol/l).
How can we interpret results of the insulin-hypoglycemia test for GH?
- Children : GH deficiency if GH<3ng/mL
- Adults : GH deficiency if GH<7ng/mL
What is the therapy for GH-deficiency?
- Glucocorticoid substitution
- L-Thyroxine
- Substitution with sex hormones (for growth, development and fertility)
- GH substitution (daily)
What are the types of glucocorticoid substitutions?
- Hydrocortisone - 15-20 mg/D - highest dose in the morning.
- Prednisolone 5 mg/D.
- Strong increase in acute cases (e.g. 3x100 mg Hydrocortison/D intravenously in shock, surgery).
What is the dose of L-thyroxine used?
Based on weight : 1.6-1.8 ug/kg/D so in general 100-150 ug/D
What are the main forms of Diabetes insipidus?
- Central Diabetes insipidus,
- Nephrogenic diabetes insipidus,
- Transient Diabetes insipidus during pregnancy,
- “Primary Polydipsia.”
What are the main causes of central Diabetes insipidus?
- Trauma,
- neurosurgery (for a pituitary tumor),
- tumors of the hypothalamus and pituitary,
- rare inflammatory diseases (sarcoidosis),
- intracranial bleeding,
- Sheehan Syndrome
- very rare congenital forms
What are the main symptoms and diagnosis of Diabetes insipidus?
- Polyuria,
- Polydipsia,
- Low urine density and osmolality (<200 mosmol/kg)
Diagnosis of central diabetes insipidus
- 2 step water deprivation test
- Saline infusion test (20 ml/kg water and 0.9% NaCl for 2 days)
What is the main treatment for central DI?
ADH-analogue Desmopressin, DDAVP, mostly as nasal spray, also available as tablets.
What are the two main forms of nephrogenic DI?
- Rare congenital forms (VP2 or AQP2 mutations)
- acquired forms (chronic renal diseases, metabolic disorders/hypercalcemia, hypokalemia, gout)
What is the recommended treatment for nephrogenic DI?
- NSAIDs : reduces the polyuria, increases osmolality.
- Mild volume depletion, thiazides in combination with NSAID. K-sparing diuretics (amiloride) + thiazides is also effective.
What are the main causes of SIADH syndrome?
Paraneoplastic syndromes (mainly lung cancer), CNS diseases.
What are the main characteristics of SIADH syndrome?
- Hyponatremia,
- low serum osmolality,
- high urine osmolality,
- relatively high urinary sodium concentration in relation to the serum.
What is the treatment for acute severe hyponatremia caused by SIADH?
- Na-supplementation in infusion (hypertonic NaCl solution or addition of NaCl).
- The rise of serum Na cannot exceed 12 mmol/L/24 h (0.5 mmol/L/hour) to avoid central pontine myelinolysis (demyelinisation damage).
What is the treatment for chronic hyponatremia caused by SIADH?
- Fluid restriction (800-1200 mL/d),
- Carbamide (urea)
