Fa: Endocrine - Pathology - 4

Front 1

If you have a patient with intense thirst, polyuria, and inability to concentrate urine, what diagnosis should you think of?

Back 1

Diabetes Insipidus

Front 2

What are the types of Diabetes Insipidus? Basic issue?

Back 2

- Central DI: lack of ADH
- Nephrogenic DI: insensitivity to ADH

Front 3

What are possible causes of Central Diabetes Insipidus?

Back 3

- Pituitary tumor
- Auto-immune process
- Trauma
- Surgery
- Ischemic encephalopathy
- Idiopathic

Front 4

What are possible causes of Nephrogenic Diabetes Insipidus?

Back 4

- Hereditary (ADH receptor mutation)
-2° to hypercalcemia, lithium, demeclocycline (ADH antagonist)

Front 5

If you have a patient with intense thirst, polyuria, and inability to concentrate urine, and you get the following lab results, what diagnosis should you make?
- ↓ ADH
- Urine specific gravity <1.006
- Serum osmolarity >290 mOsm/L
- Hyperosmotic volume contraction

Back 5

Central Diabetes Insipidus
* Only way to distinguish from Nephrogenic is based on ↓ ADH

Front 6

If you have a patient with intense thirst, polyuria, and inability to concentrate urine, and you get the following lab results, what diagnosis should you make?
- Normal ADH
- Urine specific gravity <1.006
- Serum osmolarity >290 mOsm/L
- Hyperosmotic volume contraction

Back 6

Nephrogenic Diabetes Insipidus
* Only way to distinguish from Central is based on normal ADH

Front 7

What are the following values in diabetes insipidus:
- ADH level
- Urine specific gravity
- Serum osmolarity
- Type of volume contraction

Back 7

- ADH: ↓ if central or normal if nephrogenic
- Urine specific gravity: < 1.006 (dilute)
- Serum osmolarity >290 mOsm/L (concentrated)
- Hyperosmotic volume contraction

Front 8

How do you diagnose Central Diabetes Insipidus?

Back 8

Water restriction test:
- No water intake for 2-3 hours
- Followed by hourly measurements of urine volume / osmolarity and plasma Na+ concentration / osmolarity

* Central: >50% ↑ in urine osmolarity
* Nephrogenic: no change in urine osmolarity

Front 9

What should you do if after a water restriction test normal values are not clearly reached?

Back 9

Give DDAVP (ADH analog) - this will improve central diabetes insipidus

Front 10

How do you treat central diabetes insipidus?

Back 10

- Intranasal DDAVP (ADH analog)
- Hydration

Front 11

How do you treat nephrogenic diabetes insipidus?

Back 11

- HCTZ, indomethacin, amiloride
- Hydration

Front 12

What can cause excessive water retention, hyponatremia, urinary Na+ excretion, and urine osmolarity > serum osmolarity?

Back 12

SIADH: Syndrome of Inappropriate Anti-Diuretic Hormone

Front 13

What are the findings of SIADH?

Back 13

- Excessive water retention
- Hyponatremia w/ continued urinary Na+ exretion
- Urine osmolarity > serum osmolarity

Front 14

How does the body normally respond to water retention?

Back 14

↓ Aldosterone (hyponatremia) to maintain near-normal volume status

Front 15

What are the possible consequences of the hyponatremia in SIADH?

Back 15

Can lead to cerebral edema and seizures

Front 16

When correcting hyponatremia in SIADH, what do you need to do? Why?

Back 16

Correct hyponatremia slowly to prevent central pontine myelinolysis

Front 17

What are the possible causes of SIADH?

Back 17

- Ectopic ADH (small cell lung cancer)
- CNS disorders / head trauma
- Pulmonary disease
- Drugs (eg, cyclophosphamide)

Front 18

How do you treat SIADH?

Back 18

- Fluid restriction
- IV hypertonic saline
- Conivaptan (ADH inhibitor)
- Tolvaptan (ADH receptor antagonist)
- Demeclocycline (ADH antagonist)

Front 19

What can cause under-secretion of pituitary hormones (hypo-pituitarism)?

Back 19

- Non-secreting pituitary adenoma, craniopharyngioma
- Sheehan syndrome
- Empty sella syndrome
- Brain injury, hemorrhage
- Radiation

Front 20

What tumors can cause hypo-pituitarism?

Back 20

- Non-secreting pituitary adenoma
- Craniopharyngioma

Front 21

What is Sheehan syndrome?

Back 21

Ischemic infarct of pituitary following post-partum bleeding, usually presents with a failure to lactate (no prolactin being released because of pituitary damage)

Front 22

What causes empty sella syndrome? Effect?

Back 22

- Atrophy or compression of pituitary, often idiopathic
- Common in obese women
- Leads to hypopituitarism

Front 23

What kind of brain injury can cause hypo-pituitarism?

Back 23

- Hemorrhage (pituitary apoplexy)
- General brain trauma
- Radiation

Front 24

How do you treat hypo-pituitarism?

Back 24

Hormone replacement therapy:
- Corticosteroids
- Thyroxine
- Sex steroids
- Human growth hormone

Front 25

What cause of hypo-pituitarism is common in obese women?

Back 25

Empty Sella Syndrome
- Atrophy or compression of pituitary, often idiopathic