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Renal - Awesome
Hyponatremia pp 329
Question | Answer |
---|---|
What is DDAVP? | It is an ADH analog – anti-diuresis (increases reabsorption of free water by increasing aquaporins) and stimulate release of von Willebrand factor (tx vWF deficiency) and Factor VIII (tx hemophilia A) |
In which ADH abnormalities do you have hypernatremia? In which conditions do you have hyponatremia? | Diabetes insipidus (central or nephrogenic) has hypernatremia. Hyponatremia includes psychogenic polydipsia and SIADH. |
What is central diabetes insipidus? | ADH is not being produced in the posterior pituitary. Conditions that caused this include: sarcoid, trauma, thyroid conditions. |
Where is ADH released from? | Posterior pituitary |
how can you tell the difference between central diabetes insipidus, and nephrogenic diabetes insipidus? | In central diabetes insipidus, urine osmolality will significantly increase when you give DDAVP (and ADH analog) |
How to treat central diabetes insipidus? | Give DDAVP |
How to treat nephrogenic diabetes insipidus? | Give low-dose hydrochlorothiazide to compare free water excretion. |
How to treat SIADH? | Give tolvaptan, which blocks ADH receptors. Can also give demeclocycline, which blocks the function of the ADH cascade. |
How to tell the difference between psychogenic polydipsia and SIADH? | Both cause hyponatremia, but urine sodium and urine osmolality in SIADH is higher. After the water deprivation test, the urine osmolality for SIADH does not change, but the urine osmolality for psychogenic polydipsia will increase. |
What medication blocks ADH receptors? | Lithium |
What is cerebral salt wasting? | CNS disease/subarachnoid hemorrhage --> decreased renal sodium reabsorption --> hyponatremia |
What is the range of normal serum sodium? | 135 to 145 |
What is the normal range for urine sodium? | 20 - 40 |
What is normal urine osmolarity? | 600 |
What normally happens to urine osmolarity after a fluid restriction? | Urine osmolarity increases |
What normally happens to urine osmolarity when a patient is given DDAVP? | |
What is DDAVP? | It is the equivalent of ADH. It increases our proportions and increases reabsorption of free water. |
What is nephrogenic diabetes insipidus? | The brain is producing ADH, but the kidneys are insensitive to it, so the patient cannot reabsorb free water. |
What happens to urine osmolarity in central diabetes insipidus after water deprivation? After DDAVP? | No change after water deprivation because the body does not make ADH in response to lower volume. However, if you give DDAVP, which is the equivalent of ADH, then urine osmolarity will increase. |
What happens to urine osmolarity in nephrogenic diabetes insipidus after water deprivation? After DDAVP? | No change after either, because the kidney is not sensitive to either the brain's secretion of ADH or synthetic ADH. |
What is the cheapest way to figure out if a patient has psychogenic polydipsia? | Patient with hyponatremia, low urine sodium, low urine specific gravity <1.005 |
What happens in psychogenic polydipsia after water deprivation? After giving DDAVP? | Urine osmolarity goes up in both cases, because renal function is normal. |
What is the disease when you have hyponatremia with high urine sodium and high urine osmolarity? | SIADH |
Na 146, UNa 10, UOsm 73. UOsm p H2O restrict --> 76. UOsm p DDVP pp> 600. Central DI, nephrogenic DI, psychogenic polydipsia, SIADH, hyponatremia dehydration, hpato renal syndrome? | Central DI |
Na 148, UNa 12, UOsm 71. UOsm p H2O restrict --> 75. UOsm p DDVP pp> 77. Central DI, nephrogenic DI, psychogenic polydipsia, SIADH, hyponatremia dehydration, hpato renal syndrome? | Nephrogenic DI |
Na 131, UNa 12, UOsm 65. UOsm p H2O restrict --> 500. UOsm p DDVP pp> 600. Central DI, nephrogenic DI, psychogenic polydipsia, SIADH, hyponatremia dehydration, hpato renal syndrome? | Psychogenic polydipsia |
Na 132, UNa 65, UOsm 600. Young female, recent surgery or lung CA. Central DI, nephrogenic DI, psychogenic polydipsia, SIADH, hyponatremia dehydration, hpato renal syndrome? | SIADH |
Nursing home pt. Na 160, UNa 10, UOsm 800. | Hypernatremic dehydration |
Na 130, UNa 5, Hx liver dz. | Hepatorenal Syndrome |
How to treat hypernatremic dehydration? | Tx first with NS and then with D5W |