Fluids

Question 1

Equation for calculating osmolality

Answer 1

2*Na + (bun/2.8) + (glucose/18)

Question 2

Causes of normal anion gap acidosis

Answer 2

USEDCARP

Ureterostomy
Small bowel fistula
Extra chloride
Diarrhea
Carbonic anhydrase inhibitor use 
Adrenal insufficiency 
Renal tubular acidosis 
Pancreatic fistula

Question 3

Findings with distal RTA (type 1)

Answer 3

Distal tubule not working so can’t dump acid

Urine will have a high pH > 5.5

Metabolic acidosis, hyperchloremia, hypokalemia

Question 4

Findings in proximal RTA (type 2)

Answer 4

Proximal tubule cannot reabsorb bicarb but distal tubule still working (dumps acid)

Urine pH is low < 5.5

Metabolic acidosis, hyperchloremia, hypokalemia

Question 5

Causes of acidosis with an elevated anion gap

Answer 5

MUD PILES

Methanol
Uremia
DKA
Paraldehyde 
Ingestion - iron, isoniazid 
Lactic acid 
Ethanol/ ethylene glycol 
Salicylates

Question 6

How does DI present

Answer 6

Hypernatremia

High serum osmolality with inappropriately dilute urine

Question 7

Types of DI and differences

Answer 7

Central (lack of ADH) - will respond to vasopressin

Neohrogenic (resistance to ADH) - doesn’t respond to vasopressin. X linked.

Question 8

Tx for SIADH

Answer 8

Fluid restriction

3 percent sodium chloride if Na <120

Demeclocycline in kids > 8yrs if no clinical improvement with appropriate fluid restriction

Question 9

Medications that cause hyponatremia

Answer 9

Vincristine - SIADH
Cyclophosphamide - decreased water excretion
Chlorpropamide - stimulates vasopressin
Thiazides - blocks renal sodium and chloride reabsorption

Question 10

Total body sodium in pseudohyponatremia

Answer 10

Elevated

This will present in a case with edema as in nephrotic syndrome and TG and plasma protein will be high - since these bind sodium the reported value would be low but in reality the total body sodium is high

Question 11

Rapid correction of hyponatremia can lead to what

Answer 11

Cerebral pontine myelinosis

Question 12

Ekg changes with hypokalemia

Answer 12

Flattening of T waves
ST depression
Premature ventricular beats

In extreme cases U wave after the T

Question 13

Electrolyte abnormalities that can present with weakness and EKG changes

Answer 13

Hypokalemia
Hypocalcemia
Hypomagnesemia

Question 14

Ekg changes in hypocalcemia

Answer 14

Prolongued QT interval

Question 15

Ekg changes with hypomagnesemia

Answer 15

Prolonged PR or QT interval

Question 16

Ekg changes with hyperkalemia

Answer 16

Peaked T waves and short QT interval

Then… wide QRS and increased PR interval

Then… loss p wave and sine wave pattern

Then… flat line

Can have muffled heart sounds with non palpable pulses (electromagnetic dissociation)