Fluids-Electrolytes

Question 1

What are the complications of hypercalcemia?

Answer 1

“Bones, stones, abdominal moans, psychiatric overtones.”

Bones: osteoporosis, osteomalacia, fractures, osteitis fibrosis cystica
Stones: Nephrolithiasis, nephrocalcinosis and nephrogenic diabetes insipidus
Abdominal groans: nausea, vomiting, constipation
Psychiatric overtones: coma, delirium, depression, fatigue, psychosis

Question 2

What is the initial treatment for hypercalcemia?

Answer 2

IV hydration

Question 3

What is the treatment for hypercalcemia due to immobilization?

Answer 3

IV hydration + loop diuretics

Question 4

What are the symptoms of hypocalcemia?

Answer 4

Ca level < 8.5
iCal < 4.5

Paresthesias, tetany, seizures that do not respond to benzodiazepines, laryngospasm, prolonged QT

Question 5

What crystals are associated with ethylene glycol poisoning?

Answer 5

Calcium oxalate crystals in the urine

Question 6

What symptoms are associated with hypokalemia?

Answer 6

Constipation, lethargy, weakness

Question 7

What are the findings in SIADH?

Answer 7

• Excess ADH secretion -> excess water retention -> increased total body water
• Decreased urine output
• Serum hyposmolality and hyponatremia
• Concentrated urine
• Normal/high urine sodium

Question 8

How is SIADH treated?

Answer 8

• Fluid restriction
• Demeclocycline (diuretic) or Fludrocortisone if fluid restriction is not working and sodium level is persistently less than 120

Question 9

What are the two causes of diabetes insipidus?

Answer 9

Central diabetes insipidus

Nephrogenic diabetes insipidus

Question 10

What are the features of central diabetes insipidus?

Answer 10

• Insufficient ADH -> constant water loss
• Hypernatremia when the patient does not have access to free water
• Polyuria and dilute urine
• Treat with DDAVP/ADH

Question 11

What are the features of nephrogenic diabetes insipidus?

Answer 11

• X-linked recessive
• Massive urine output
• No response to DDAVP/ADH supplementation
• Hypernatremia
• Tx: hydrochlorothiazide, salt restriction

Question 12

What is the formula for corrected calcium?

Answer 12

Add 0.8 to the calcium level for every drop in albumin of 1 g/dL

Question 13

How is the sodium level affected by hyperglycemia?

Answer 13

Sodium decreases by 1.6 for every 100 increase in glucose

Question 14

How do you calculate the anion gap?

Answer 14

Na+ - Cl- - HCO3-

Question 15

What is the adjusted anion gap for hypoalbuminemia?

Answer 15

(4-pt albumin) x 2.5 = x

12-x = anion gap max normal

Question 16

How do you calculate the expected PCO2?

Answer 16

(1.5 x HCO3-) + 8 +/- 2

Question 17

How do you calculate for sodium correction?

Answer 17

(desired Na - measured Na) x wt(kg) x 0.6 + 3 mEq/kg (for maintenance Na requirements) = amount of sodium needed in 24 hours
* Note: never correct more than 12 mEq/day

Question 18

How do you calculate FeNa?

Answer 18

• A calculation that tells you how much Na+ is excreted as compared to reabsorbed

= (UNa+ / UCr) / (PNa+ / PCr)

<1% = prerenal disease, low renal perfusion
>2% = tubular/glomerular damage