Electrolytes Flashcards
How can diabetes result in hyperkalemia?
Decrease in insulin, hyperosmolar state, water leaves cell resulting in increase in intracellular [K+], K+ leaves cell
What is the familial hyperaldosteronism genetic mutation?
KCNJ5
What is the name of the disease in which aldosterone is expressed in the zona fasiculata?
Glucocorticoid remediable aldosteronism
Condition causing hypertension with hyperkalemia?
Gordon’s Syndrome (activation in WNK1/ deactivation in WNK4 stimulating NCC)
Underlying mechanism of Liddle Syndrome?
Hyperfunctioning ENaC
Underlying mechanism of Bartter Syndrome?
Malfunctioning NKCC2
Underlying mechanism of Gittleman Syndrome?
Malfunctioning NCC
How do you diagnose primary hyperaldosteronism using ARR?
ARR > 20
Name 3 drugs that increase ARR?
1) Beta blockers
2) Clonidine
3) NSAIDs
Name 4 drugs that decrease ARR?
1) ACEi
2) ARB
3) Amlodipine/Nifedipine
4) Potassium sparring diuretics
What sum of urine Na+ and urine K+ indicates that ADH is turned off?
< 50
A stroke involving what vessel can result in impaired thirst?
Right anterior communicating artery
What is a lab that can be checked to see if vasopressin is being synthesized?
Copeptin
What is the pathophysiology and treatment for gestational diabetes insipidus?
Placental synthesis of vasopressinase
Tx = desmopressin
How can a water deprivation test be used to differentiate between diabetes insipidus and polydipsia?
@ serum osmolarity of 295
- Urine osmolarity > 500 = polydipsia
- Urine osmolarity < 300 = diabetes insipidus
What are some causes of central diabetes insipidus?
Stroke
Trauma
Autoimmune (SLE)
What are some causes of nephrogenic diabetes insipidus?
Hypercalcemia (V2 receptor issues)
Hypokalemia (collecting duct cysts)
Lithium
What drug used to treat CMV can result in hypocalcemia?
Foscarnet
What type of imaging contrast can result in pseudohypocalcemia?
Gadolinium
How does obstruction impact ENaC?
Decreased expression
How do loop diuretics cause hypomagnesemia?
By blocking NKCC, the secretion of K+ back into lumen is impaired resulting in less paracellular Mg2+ reabsorption
How does hypomagnesemia lead to hypokalemia?
Hypomagnesemia results in ROMK to be persistently open in collecting duct
How do you calculate Free Water Clearance?
= V * [1 - (UNa+UK/SNa)]
How do you calculate Free Water Deficit?
= 0.6 * W * [(SNa/140) - 1]
How do you correct sodium for hyperglycemia?
For every 100 mg/dl above 100 mg/dl, add 1.6 to SNa
Which drug used for induction treatment of ANCA associated vasculitis can result in hyponatremia?
Cyclophosphamide
What is the treatment for nephrogenic diabetes insipidus due to Li2+ if patient is still on Li2+ and, in contrast, if the patient is off of Li2+?
On Li2+: use amiloride
Off Li2+: use thiazide
What is the next best test following diagnosis of hypokalemic periodic paralysis?
TSH
How do the urine chloride levels differ with diarrhea and emesis?
Diarrhea = high urine chloride
Vomiting = low urine chloride
What chemotherapy agents can cause hypomagnesemia?
Cisplatin
Cetuximab
Barium exposure can result in what electrolyte disorder?
Hypokalemia
Pathophysiology of autosomal dominant hypocalcemia?
Activating mutation in CaSR
How do you calculate total Na+ intake using 24 hour urine Na+?
23 * 24 hour urine Na+
Toluene is associated with what electrolyte disorder?
Hypokalemia
Bartter and Gitleman can be differentiated by what urine test finding?
High urine Ca2+ in Bartter
What ratio of urine K to urine Cr can be used to assess for renal potassium conservation?
Urine K:Urine Cr < 15 mEq/g
(K+ < 25 mEq/L if 24 hour sample)
What is the formula to estimate total free water need in a patient with hypernatremia?
FWC + FWD + 0.8 liters
What lab will be elevated with hypercalcemia of immobilization?
N telopeptide
Piperacillin use is associated with what electrolyte abnormality?
Hypokalemia
Patiromer is associated with what electrolyte abnormality?
Hypomagnesemia
Sodium retention and edema is associated with which potassium binder?
Sodium zirconium
Octreotide is associated with what electrolyte abnormality?
Hyperkalemia (inhibits insulin release)
What is the approximate urine Na+ (mEq/d) to estimate 2 grams of daily intake?
88 mEq/d
A defect in _____________ is seen with Familial Hypocalcemia Hypercalciuria NephroCalcinosis?
Claudin-16
How can a water load be used to evaluate for reset osmostat vs SIADH?
Majority excreted within 4 hours is consistent with reset osmostat (minimal excretion with SIADH)
Contrast aldosterone breakthrough, aldosterone escape, and aldosterone paradox?
Aldosterone breakthrough: increase in aldosterone levels following period of time after ACEi/ARB initiation
Aldosterone escape: Na+ absorption without associated edema in primary hyperaldosteronism due to pressure naturiesis
Aldosterone paradox: no hypokalemia with hyperaldosteronism states due to WNK4 ROMK inhibition
Leptospirosis is associated with what electrolyte abnormality?
Hypokalemia
