Endocrine Week 2 class material
what are the key management strategies for treatment of nephrogenic DI?
*Allow adequate free water intake to prevent dehydration *<500mg of sodium daily (may reduce urine volume) *low protein diet *Endocrinology consult *test serum electrolytes every 6 months
How should SIADH be managed?
*fluid restriction <800mL qd *Monitor for hyponatremia *refer to endocrinology
which pharmaceutical interventions are often used for the management of SIADH?
*loop diuretics (if urine osmolality is more than twice plasma osmolality) *Demeclocycline & lithium (diminish tubule response to ADH) *Arginine vasopressin receptor antagonists aka Vaptans (Tx <30 days) *Urea orally (inc. urinary water and solute excretion)
what are the key management strategies for treatment of neurogenic DI?
*low solute diet (low sodium & low protein) *Thiazide diuretic *refer to endocrinologist & neurologist *Desmopressin (dDVAP) synthetic ADH *Pt should drink no more than to satisfy thirst (avoid risk of hyponatremia)
A vasopressin challenge test is used to...
confirm a DI diagnosis and distinguish between central and nephrogenic DI
What are the hallmark signs of SIADH?
1. hyponatremia 2. concomitant serum osmolarity 3. high urine osmolarity
What are some of the contraindications/ side effects of the following SIADH treatments? 1.Demeclocycline & lithium 2. Vaptans
1. may cause nephrogenic DI 2. contraindicated in liver Dz
Hypernatremia indicative of DI is considered
>142 meq/l
Vasopressin challenge test results indicative of central DI
>50% inc. in urine osmolality
What tests would you run to work up suspected DI?
CMP (assess for serum hyperosmolality/hypernatremia), Plasma sodium and urine osmolality- will see unconcentrated urine
What is the action of ADH?
Controls water retention. Promoted water reabsorption in the collecting ducts of the kidney
What is the DDx for a CC of polyuria?
DM, UTI, PKD, psychogenic polydipsia, BPH
to avoid osmotic demyelination syndrome...
IV hypertonic saline should be administered by a specialist
what type of imaging is recommended for pts with suspected central DI?
MRI
Overly aggressive treatment or rapid correction of hyponatremia may result in ______ & _____ leading to ________
central pontine myelinolysis (brain shrinkage)osmotic demyelination neurologic deterioration
What symptom picture would help to distinguish between central and nephrogenic DI?
central- abrupt onset of polyuria nephrogenic- gradual onset of polyuria
In SIADH the sign of hyponatremia is due to...
an excess of water in relation to sodium in the blood
Describe the presentation of a patient with SIADH
anorexia, nausea and malaise are the earliest findings. Followed by HA, irritability, confusion, muscle cramps, weakness, seizures & coma
What is the difference between central and nephrogenic diabetes insipidus?
central- problem w/ brain. decreased secretion of ADH nephrogenic- problem w/ the kidneys. lack of response to ADH
Drugs that increase the response to or secretion of ADH
chlorpropamide carbamazepine clofibrate NSAID's
SIADH is a disorder of impaired water excretion that results in...
concentrated urine and reduced urine volume
What are the signs and symptoms suggestive of DI?
dehydration dry cracked lips decreased turgor & mobility of skin polyuria polydipsia hypernatremia
Where is ADH made?
hypothalamus
ADH is released in response to ______ or ______
increased osmolarity or decreased blood volume
What would you expect to see on a positive water restriction test?
little to no increase in urine osmolality with deprivation in DI due to failure to concentrate urine
Vasopressin challenge test results indicative of nephrogenic DI
no response or <50% urine osmolality
What is a distinguishing symptom of diabetes insipidus?
nocturia (pts notice they are wetting the bed or getting up more than once to pee)
What is a common symptom of diabetes insipidus and diabetes mellitus?
polyuria
From where is ADH secreted?
posterior pituitary
SIADH is a diagnosis of exclusion. What other diagnoses should be ruled out when SIADH is suspected?
pseudohyponatremia, hyperlipidemia, hyperproteinemia, tumor, hyperglycemia, increased plasma osmolarity due to mannitol, primary sodium loss (sweating, GI, renal), hypothyroidism, chronic renal insufficiency, heart failure, nephrotic syndrome, hepatic cirrhosis
What are some causes of SIADH
small cell carcinoma of the lung, pneumonia, pituitary surgery, idiopathic (in the elderly), stroke, hemorrhage, trauma, HIV, sulfonylureas, SSRI's, TCA's, NSAID's, MDMA
What tests are used to diagnose DI?
water restriction test vasopressin challenge test
