Darrow Osmolality CIS

Question 1

most common electrolyte order we will see

Answer 1

hyponatremia

Question 2

normal serum sodium

Answer 2

normal 140 meq/L

Question 3

normal serum K

Answer 3

n = 4.5 meq/L).

Question 4

normal serum cl

Answer 4

meq/L (100)

Question 5

normal serum bicarb

Answer 5

meq/L (25).

Question 6

normal serum glucose

Answer 6

60 mg/dL(60 -100).

Question 7

normal urine osmolality

Answer 7

(50-1200)

Question 8

how to calculate serum osmolality

Answer 8

285 is normal

usually just double na

(Serum Osm= 2(Na) + BUN/2.8 + glucose/18)

Question 9

The decreased vascular volume produces decreased baroreceptor stretch with resultant

Answer 9

increased sympathetic tone to increase proximal tubular Na absorption and activate RAAS(increased Na absorption in the cortical collecting tubule). Decreased cardiac output in addition yields a decreased RBF and GFR. All these contribute to avid sodium retention and reabsorption with resultant low urinary sodium, ieUNa

Question 10

The low BV activates

Answer 10

ADH secretionwith avid water retention which
outperforms the retention of Na to yield hyponatremia, especially if the patient has increased free water intake.Almost all cases of hyponatremia(except for PP, etc) involve a relative excess of ADH, which may be appropriate or inappropriate.

Question 11

Hyponatremia

(Na

Answer 11

Artifactualpseudohyponatremia-
Extra fat and protein
Isotonic Hyponatremia
1. Hyperproteinemia(myeloma)
2. Hyperlipidemia (chylomicrons, tryaglycerides, rarely cholesterol)

Question 12

Hyponatremia

(Na

Answer 12

Hypotonic Hyponatremia

Volume Status?

Focusing on hypotonic hyponatremiathe second step is to evaluate volume status

Question 13

Hyponatremia

Na 295 mosm/kg

Answer 13

Extra carbohydrate
Hypertonic Hyponatremia
1. Hyperglycemia
2. Mannitol, sorbitol, glycerol, maltose
3. Radiocontrastagents
4. Ethylene glycol, methanol

Question 14

protein and fat dont have an effect on

Answer 14

osmolality

Question 15

Hypovolemia(32%)

Una

Answer 15

ExtrarenalSalt Loss

1. Dehydration
2. Vomiting
3. Diarrhea
4. 3rdSpacing (burns, trauma)

Question 16

Hypovolemia(32%)

Una> 20 meq/L

Answer 16

Renal Salt Loss

1. Diuretics
2. ACE Inhibitors
3. Nephropathies
4. Mineralocorticoid deficiency (Addison’s)
5. Cerebral Sodium Wasting (BNP)
6. Partial Obstruction
7. Type IV RTA

Question 17

Euvolemic(48%)

UNa+> 20mEq/L

Answer 17

1. SIADH –35% (Uosm> 200 mOsm/L)
2. Post-op hyponatremia
3. Psychogenic polydipsia –4%(Uosm

Question 18

Hypervolemic(20%)

Una

Answer 18

Edematous States

1. Congestive heart failure
2. Liver Disease
3. Nephrotic syndrome (Renal Na retention)
4. Advanced kidney disease (Una> 20 meq/L)

Question 19

if there is hypokalemia think

Answer 19

alkalosis

Question 20

for every 2 sodiums you retain you get rid

Answer 20

1 hydrogen and 1 potassium

Question 21

An EKG is done on the patient and reveals flattened to inverted T waves with U waves. What abnormality does the
EKG reveal?

Answer 21

hypokalemia

Question 22

contraction alkalosis

Answer 22

for every 2 sodiums you lose a hydrogenand potassium bc when you reabsorb k you reabsorb a bicarb with it and h takes a cl with it?

Question 23

Urea is passively reabsorbed in the proximal tubule. Thus, if volume is
low and BUN concentration high

Answer 23

there will be increased reabsorption
according to the higher BUN gradient. Also, more urea is reabsorbed at
low tubular flow rates than at high tubular flow rates.
In addition, low effective plasma volume creates a resultant increased
ADH with the latter effecting more collecting tubule reabsorptionof
BUN in order to create the gradient for water reabsorption.

Question 24

Elevated BUN

in Dehydration

Answer 24

low flow so na is actively reabsorbed so bun becomes more concentrated in the tubule so it is passively reabsorbed

Question 25

What is meaning of the BUN/creatinineratio of 60/1.4?

Answer 25

•A high BUN/Cr ratio occurs in prerenalazotemiadue to the decreased GFR with avid Na and H2O and BUN (passive) reabsorptionin the proximal tubule. At the same time creatinineis actually secreted in the proximal tubule since the kidney is functioning normally. The result is a high BUN/creatinineratio.

Question 26

Causes of an elevated BUN/creatinine

Answer 26

High protein intake or breakdown: Pre renal disease Pre renal disease

Question 27

Causes of an elevated BUN/creatinine | High protein intake or breakdown

Answer 27

Catabolic state Catabolic drugs, ietetracycline, steroids GI bleed

Question 28

Causes of an elevated BUN/creatinine | Pre renal disease

Answer 28

Dehydration CHF Shock Glomerulonephritis

Question 29

Causes of an elevated BUN/creatinine | Post renal disease

Answer 29

Prostatic obstruction | Ureteral obstruction

Question 30

BUN/creatinineof 10/1

Answer 30

indicates either normal renal function (when creatinineis 1 or less) or intrinsic renal disease (when the creatinineis > 1), ie. BUN of 40 and creatinineof 4 = 40/4 = I0/1

Question 31

BUN/creatinineratio > 10/1

Answer 31

ie. BUN of 30 with creatinineof 1 =Prerenal(including glomerulo-nephritis), or postrenalazotemia, or catabolic state

Question 32

BUN/creatinine

Answer 32

non-renal), ielow BUN seen in liver failure, malnutrition, overhydration, pregnancy, SIADH

Question 33

hyaline or tamms horsfall cast

Answer 33

prerenalazotemia.

Question 34

Urine sediment with pigmented granular casts and renal tubular epithelial cells is pathognomonic for

Answer 34

ATN

Question 35

Causes of atn

Answer 35

``` Ischemia: post op shock, sepsis pancreatitis hypophosphatemia Toxins: aminoglycosides vancomycin cyclosporine radiographic contrast media myoglobinuria hemoglobin hyperuricemia BenceJones protein ```

Question 36

protein and fat do effect?

Answer 36

effective plasma volume

Question 37

An EKG is done on the patient and shows a prolonged PR | interval with peaked T waves, indicative of:?

Answer 37

Hyperkalemia

Question 38

what must one watch out for in phosphate replacement?

Answer 38

if you give phostphate be careful bc it can cause hypocalcemia

Question 39

This patient has renal ATN due to rhabdomyolysisfrom starvation and alcohol related hypophosphatemia and subsequently decreased 2,3 DPG with oxygen starvation and tissue hypoxia. Phosphate replacement, should be done

Answer 39

slowly to avoid hypocalcemia.

Question 40

Classic crush injury rhabdomyolysiswould cause massive release of phosphate, uric acid and potassium with decreased calcium due to Cax P precipitation in tissues. In that type of situation, one would

Answer 40

notwant to administer calcium as with improvement it will be released from the tissues.

Question 41

Urine sediment of pigmented granular castsand renal tubular epithelial cells is pathognomonic for

Answer 41

ATN

Question 42

ischemic causes of ATN

Answer 42

post op shock, sepsis pancreatitis hypophosphatemia

Question 43

toxic causes of ATN

Answer 43

``` aminoglycosides vancomycin cyclosporine radiographic contrast media myoglobinuria hemoglobin hyperuricemia BenceJones protein ```

Question 44

As the renal tubular epithelium regenerates, as the double nucleus (arrow) in this photomicrograph testifies to, the kidney begins to produce large amounts of very dilute urine. The reason for this is

Answer 44

that the complicated brush border cells do not come back immediately, they are first replaced by low cuboidalepithelium, which does little in the way of resorptionof water. Thus large quantities of dilute urine (polyuria) are produced by the patient. Eventually, the epithelium differentiates into the more complex brush border type, and normal urinary production is restored.

Question 45

GO THROUGH CASES

Answer 45

NOW