Electrolytes

Question 1

How can diabetes result in hyperkalemia?

Answer 1

Decrease in insulin, hyperosmolar state, water leaves cell resulting in increase in intracellular [K+], K+ leaves cell

Question 2

What is the familial hyperaldosteronism genetic mutation?

Answer 2

KCNJ5

Question 3

What is the name of the disease in which aldosterone is expressed in the zona fasiculata?

Answer 3

Glucocorticoid remediable aldosteronism

Question 4

Condition causing hypertension with hyperkalemia?

Answer 4

Gordon’s Syndrome (activation in WNK1/ deactivation in WNK4 stimulating NCC)

Question 5

Underlying mechanism of Liddle Syndrome?

Answer 5

Hyperfunctioning ENaC

Question 6

Underlying mechanism of Bartter Syndrome?

Answer 6

Malfunctioning NKCC2

Question 7

Underlying mechanism of Gittleman Syndrome?

Answer 7

Malfunctioning NCC

Question 8

How do you diagnose primary hyperaldosteronism using ARR?

Answer 8

ARR > 20

Question 9

Name 3 drugs that increase ARR?

Answer 9

1) Beta blockers
2) Clonidine
3) NSAIDs

Question 10

Name 4 drugs that decrease ARR?

Answer 10

1) ACEi
2) ARB
3) Amlodipine/Nifedipine
4) Potassium sparring diuretics

Question 11

What sum of urine Na+ and urine K+ indicates that ADH is turned off?

Answer 11

< 50

Question 12

A stroke involving what vessel can result in impaired thirst?

Answer 12

Right anterior communicating artery

Question 13

What is a lab that can be checked to see if vasopressin is being synthesized?

Answer 13

Copeptin

Question 14

What is the pathophysiology and treatment for gestational diabetes insipidus?

Answer 14

Placental synthesis of vasopressinase
Tx = desmopressin

Question 15

How can a water deprivation test be used to differentiate between diabetes insipidus and polydipsia?

Answer 15

@ serum osmolarity of 295
- Urine osmolarity > 500 = polydipsia
- Urine osmolarity < 300 = diabetes insipidus

Question 16

What are some causes of central diabetes insipidus?

Answer 16

Stroke
Trauma
Autoimmune (SLE)

Question 17

What are some causes of nephrogenic diabetes insipidus?

Answer 17

Hypercalcemia (V2 receptor issues)
Hypokalemia (collecting duct cysts)
Lithium

Question 18

What drug used to treat CMV can result in hypocalcemia?

Answer 18

Foscarnet

Question 19

What type of imaging contrast can result in pseudohypocalcemia?

Answer 19

Gadolinium

Question 20

How does obstruction impact ENaC?

Answer 20

Decreased expression

Question 21

How do loop diuretics cause hypomagnesemia?

Answer 21

By blocking NKCC, the secretion of K+ back into lumen is impaired resulting in less paracellular Mg2+ reabsorption

Question 22

How does hypomagnesemia lead to hypokalemia?

Answer 22

Hypomagnesemia results in ROMK to be persistently open in collecting duct

Question 23

How do you calculate Free Water Clearance?

Answer 23

= V * [1 - (UNa+UK/SNa)]

Question 24

How do you calculate Free Water Deficit?

Answer 24

= 0.6 * W * [(SNa/140) - 1]

Question 25

How do you correct sodium for hyperglycemia?

Answer 25

For every 100 mg/dl above 100 mg/dl, add 1.6 to SNa

Question 26

Which drug used for induction treatment of ANCA associated vasculitis can result in hyponatremia?

Answer 26

Cyclophosphamide

Question 27

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+?

Answer 27

On Li2+: use amiloride Off Li2+: use thiazide

Question 28

What is the next best test following diagnosis of hypokalemic periodic paralysis?

Answer 28

TSH

Question 29

How do the urine chloride levels differ with diarrhea and emesis?

Answer 29

Diarrhea = high urine chloride Vomiting = low urine chloride

Question 30

What chemotherapy agents can cause hypomagnesemia?

Answer 30

Cisplatin Cetuximab

Question 31

Barium exposure can result in what electrolyte disorder?

Answer 31

Hypokalemia

Question 32

Pathophysiology of autosomal dominant hypocalcemia?

Answer 32

Activating mutation in CaSR

Question 33

How do you calculate total Na+ intake using 24 hour urine Na+?

Answer 33

23 * 24 hour urine Na+

Question 34

Toluene is associated with what electrolyte disorder?

Answer 34

Hypokalemia

Question 35

Bartter and Gitleman can be differentiated by what urine test finding?

Answer 35

High urine Ca2+ in Bartter

Question 36

What ratio of urine K to urine Cr can be used to assess for renal potassium conservation?

Answer 36

Urine K:Urine Cr < 15 mEq/g (K+ < 25 mEq/L if 24 hour sample)

Question 37

What is the formula to estimate total free water need in a patient with hypernatremia?

Answer 37

FWC + FWD + 0.8 liters

Question 38

What lab will be elevated with hypercalcemia of immobilization?

Answer 38

N telopeptide

Question 39

Piperacillin use is associated with what electrolyte abnormality?

Answer 39

Hypokalemia

Question 40

Patiromer is associated with what electrolyte abnormality?

Answer 40

Hypomagnesemia

Question 41

Sodium retention and edema is associated with which potassium binder?

Answer 41

Sodium zirconium

Question 42

Octreotide is associated with what electrolyte abnormality?

Answer 42

Hyperkalemia (inhibits insulin release)

Question 43

What is the approximate urine Na+ (mEq/d) to estimate 2 grams of daily intake?

Answer 43

88 mEq/d

Question 44

A defect in _____________ is seen with Familial Hypocalcemia Hypercalciuria NephroCalcinosis?

Answer 44

Claudin-16

Question 45

How can a water load be used to evaluate for reset osmostat vs SIADH?

Answer 45

Majority excreted within 4 hours is consistent with reset osmostat (minimal excretion with SIADH)

Question 46

Contrast aldosterone breakthrough, aldosterone escape, and aldosterone paradox?

Answer 46

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

Question 47

Leptospirosis is associated with what electrolyte abnormality?

Answer 47

Hypokalemia