Nephrology Board Review

1
Nephrology Board Review

• Sidharth Shah, MD.
• June 2007

2
Make sure you know.

• Hyponatremia
• Hypernatremia (H20 deficit)
• ETOH ketoacidosis
• RF 2/2 atheroembolic disease (cholesterol emboli)
• Obstructive uropathy
• Indinavir --gt crystal nephropathy
• Stage 2 HTN

3
Question 1

• 42 yo male brings in his 10yr old son as hes
  concerned that the child is happy all the time
  and appears to be like a puppet. What syndrome
  does the child likely have?

4
Nephrology MKSAP Q87

• 64 yo male admitted with a 5 day history of
  lethargy and mild confusion. He is known to have
  alcoholic cirrhosis, nonbleeding esophageal
  varicies, ascites. There is no history of
  recent ETOH consumption, melena, or hematemesis.
  No co abdominal pain has not fallen. Hes on a
  2gm Na diet and takes a MVI qday.
• Exam
• VS BP 110/70, HR 87bpm, Temp 36. Icteric
  sclerae, and spider angiomata present. No JVD.
  Lungs are clear, with decreased breath sounds as
  both bases. Cardiac HRRR. No gallop, rub.
  Abdomen is protruberent but not tender, with a
  shifting dullness. Liver is not palpable.
  Extremities show 1 ankle edema. Asterixis is
  present, but the patient has not focal neurologic
  signs.

5
Nephrology MKSAP Q87

• Labs
• Hgb 11.5g/dl
• HCT 32
• PLT 84,000/uL
• WBC 5400/uL
• Serum BUN 20mg/dl
• Serum Cr 1.2mg/dl
• Serum Na114meq/dl
• Serum K 4.1meq/L

• Serum Cl 80meq/L
• Serum HC03 28meq/K
• Serum total protein 6.9g/dl
• Serum Alb 2.5g/dl
• Cholesterol 186mg/dl
• Serum Osm241 mosmol/kg H20
• Urine Osm 200mosmol/kg H20
• Spot Urine Na 10meq/L

6
Nephrology MKSAP Q87

• What is the cause of this patients hyponatremia?
• Nonosmotic stimulation of ADH
• Hepatorenal syndrome
• Low-Na diet
• Reset osmostat
• Pseudohyponatremia

7
Nephrology MKSAP Q87

• What is the cause of this patients hyponatremia?
• Nonosmotic stimulation of ADH
• Hepatorenal syndrome Hyponatremia can be seen in
  HRS, but does not cause it.
• Low-Na diet Never associated with hyponatremia
• Reset osmostat Would have appropriate dilute
  urine
• Pseudohyponatremia Occurs in high serum levels
  of protein or lipids.

8
Hyponatremia Workup

• 1) Measure plasma osmolality
• Hypertonic hypo Na excess of another effective
  osmole (glc, mannitol)
• Each 100mg/dl increase in glc gt100mg/dl leads to
  a decrease of Na by 2.4meq/L
• Isotonic hypo Na lab artifact from
  hyperlipidemia or hyperproteinemia

9
Hypotonic Hyponatremia
Hypotonic Hyponatremia
Hypovolemic Hyponatremia
Euvolemic Hyponatremia

• Hypervolemic
• Hyponatremia

Uosmgt100
Uosmlt100
Uosm var.
Unalt 10 FeNalt 1
Unagt 20 FeNagt 1
Unalt10 FeNalt1
Unagt 20 FeNagt 1
Renal Losses
Extra-renal Losses
SIADH Adrenal Insuf Hypothyroid
1 polydipsia Low Solute
Reset osmostat
CHF Cirrohsis Nephrosis
Renal Failure
10
Harrisons VIII-29

• 36 yo male undergoes knee surgery to repair torn
  ligaments. Postop, he is prescribed APAP for
  pain. One day later he reports worsening pain.
  Exam reveals BP 120/75, HR 80/min, RR 14/min and
  temp 98.6F. He has severe pain at the knee but no
  redness or signs of infection.
• Lytes
• Na 128meq/L K 4.0meq/L
• Cl 95mg/dl Bicarb 25mg/dl
• BUN 12mg/dl Cr 1.0mg/dl

11
Harrisons VIII-29

• Which of the following therapies is most
  appropriate at this time?
• Hypertonic saline
• Furosemide
• Morphine
• Normal Saline
• Vancomycin
• Fluid restriction

12
Harrisons VIII-29

• 36 yo male undergoes knee surgery to repair torn
  ligaments. Postop, he is prescribed APAP for
  pain. One day later he reports worsening pain.
  Exam reveals BP 120/75, HR 80/min, RR 14/min and
  temp 98.6F. He has severe pain at the knee but no
  redness or signs of infection.
• Lytes
• Na 128meq/L K 4.0meq/L
• Cl 95mg/dl Bicarb 25mg/dl
• BUN 12mg/dl Cr 1.0mg/dl

13
Harrisons VIII-21

• 33yo male is brought for medical attention after
  completing a marathon. Upon finishing, he was
  disoriented and light-headed. His normal weight
  is 60kg. Exam reveals a body temp of 38.3, BP
  85/60mmHg and HR 125/min. Neck veins are flat,
  skin turgor is poor. Serum Na is 175meq/L. What
  is the free H20 deficit?

14
Harrisons VIII-21

• Free H20 deficit
• Na- 140 x (total body water)
• 140
• 175-140 x (60kg)(0.5)
• 140
• 0.25 x 30 7.5L
• Desired change in Na 175meq-140meq 35meq
• 35meq x __1hr__ 70hrs
• 0.5meq

15
Harrisons VIII-50

• 72 yo male develops ARF after cardiac cath. Exam
  is notable for diminished peripheral pulses,
  livedo reticularis, epigastric tenderness, and
  confusion. Labs show BUN 131, Cr 5.2, Phos 9.5.
  UA 10-15 WBC, 5-10 RBC, and 1 hyaline cast/HPF.

16
Harrisons VIII-50

• What is the diagnosis?
• AIN caused by drugs
• Rhabdomyolysis with ATN
• ATN 2/2 radiocontrast exposure
• Renal arterial dissection with prerenal azotemia
• Cholesterol emobolization

17
Harrisons VIII-50

• 72 yo male develops ARF after cardiac cath. Exam
  is notable for diminished peripheral pulses,
  livedo reticularis, epigastric tenderness, and
  confusion. Labs show BUN 131, Cr 5.2, Phos 9.5.
  UA 10-15 WBC, 5-10 RBC, and 1 hyaline cast/HPF.

18
Cholesterol Atheroembolic Renal Disease

• Pathophysiology
• Showers of cholesterol emboli what can cause
  stepwise progression of renal failure
• Characterized by
• Pyuria
• Progressive RF (nonoliguric)
• Hypocomplementemia
• Eosinophiluria
• Associated organ dysfunction

19
Harrisons VIII-9

• In the ED, a male patient presents with right
  flank pain without radiation during micturition
  and intermittent polyuria with other periods of
  decreased urine output. Denies having dysuria,
  hematuria, and fever. Denies any PMHx, and ROS is
  negative.
• Exam shows VSS, and normal abdominal exam except
  for mild costophrenic angle tenderness on the
  right. Rectal exam shows no tenderness, and there
  is a normal prostate examination. No edema is
  note to the lower extremities. UA is bland
  without pyuria, bacteria, or casts. Serum BUN/Cr
  50/2.0mg/dl. Renal U/S shows bilateral
  hydronephrosis.

20
Harrisons VIII-9

• What is the diagnosis?
• Acute cystitis
• Genitourinary TB
• Nephrolithiasis
• Transitional cell ca of the bladder
• Vesicoureteral reflux disease

21
Harrisons VIII-9

• In the ED, a male patient presents with right
  flank pain without radiation during micturition
  and intermittent polyuria with other periods of
  decreased urine output. No dysuria, hematuria,
  and fever reported. Denies any PMHx, and ROS is
  negative.
• Exam shows VSS, and normal abdominal exam except
  for mild CVA tenderness on the right. Rectal
  exam shows no tenderness, and there is a normal
  prostate examination. No edema is note to the
  lower extremities. UA is bland without pyuria,
  bacteria, or casts. Serum BUN/Cr 50/2.0mg/dl.
  Renal U/S shows bilateral hydronephrosis.

22
Obstructive Uropathy

• Pathophysiology
• Azotemia obstruction of outflow tracts of two
  normal kidneys or one in the presence of
  bilateral renal disease.
• Anuria complete obstruction
• Oliguria, frequency, polyuria, nocturia partial
  obstruction
• Labs
• High BUN/Cr decreased tubular flow and increased
  tubular reabsorption of urea
• Urine indices and Na are not reliable
• Associated with Type IV RTA (hyperkalemia)
• Remember
• Polyuria may happen as a physiologic respone OR
• Postobstructive diuresis 2/2 Na H20 retention
  and abnormal renal tubular handling of Na H20

23
MKSAP Nephrology Q23

• 63 yo factory worker presents with upper lower
  extremity diffuse muscle weakness over the past
  2 wks. For the past 6 mos, he has had low back
  pain that was sufficiently severe to cause him to
  miss work several occasions. Buffered salicylate
  tx relieved the pain somewhat.

24
MKSAP Nephrology Q23

• Labs
• Hgb 8g/dl K 2.6meq/L
• HCT 24 Na 135meq/L
• PLT 106K/ul Cl 117meq/L
• BUN 10mg/dl Bicarb 15meq/L
• Cr 1.0mg/dl Glc 88mg/dl
• Osm 277mosmol/L Cal 11mg/dl
• ABG 7.30/31 (pCO2)
• UA neg for albumin sulfosalicylic acid

25
MKSAP Nephrology Q23

• What disease process best explains the acid-base
  disorder?
• Proximal RTA
• Salicylate toxicity
• ETOH-induced lactic acidosis
• Ethylene glycol toxicity

26
RULES
Professor Fullers 5 Rules For Acid-Base
Adapted from K.Lee presentation 9/2005
27
Rules of Five -- 1

• Identify the Disorder
• pH lt 7.40 Acidemia
• pH gt 7.44 Alkalemia

Adapted from K.Lee presentation 9/2005
28
Rules of Five -- 2

• Find the Primary Disturbance
• Acidosis
• HCO3 lt 24 Metabolic
• pCO2 gt 44 Respiratory
• Alkalosis
• HCO3 gt 24 Metabolic
• pCO2 lt 40 Respiratory

Adapted from K.Lee presentation 9/2005
29
Rules of Five -- 3 Why We Dont Spark!

• ALWAYS Calculate the Anion Gap
• LAW OF ELECTRONEUTRALITY REIGNS SUPREME
• AG (Unmeasured Cations) Na K (Unmeasured
  Anions) Cl HCO3
• note K usually omitted b/c only small
  magnitude of changes in serum
• AG Na Cl HCO3 UA UC
• normal 10 (/-2) UC Ca, Mg
• UA albumin, PO4-, sulfates, other

Adapted from K.Lee presentation 9/2005
30
Rules of Five -- 3

• ALWAYS Calculate the Anion Gap
• AG gt 20 highly significant
• think about Osmolal Gap
• Osmolal Gap calcOsm measOsm lt/ 10
• measured Osm what the lab detects from your
  blood sample
• calculated Osm 2(Na) BUN/2.8 Gluc/18
  EtOH/4.6
• Rapid detection by Serum Alcohol Screen
  obviates need for
• ethylene glycol, methanol, or isopropyl alcohol
  corrections

Adapted from K.Lee presentation 9/2005
31
Rules of Five -- 3

• ALWAYS Calculate the Anion Gap
• Low Anion Gap (if AGlt7) think excess cations
• Paraproteinemias (Multiple Myeloma)
• Hypermagnesemia / Hypercalcemia
• Lithium Intoxications

Adapted from K.Lee presentation 9/2005
32
Rules of Five -- 3

• ALWAYS Calculate the Anion Gap
• Remember to correct for low albumin state
• For each drop in albumin by 1mg/dl (from
  4mg/dl), add 2.5 to your calculated Anion Gap

Adapted from K.Lee presentation 9/2005
33
Rules of Five -- 4

• Check for Compensation
• METABOLIC ACIDOSIS
• HCO3 15 pCO2
• Each fall in HCO3 by 10 mEq/L, the pCO2 should
  fall 12 mmHg
• Winters (HCO3)(1.5) 8 /- 2 pCO2
• METABOLIC ALKALOSIS
• Each rise in HCO3 by 10 mEq/L, the pCO2 should
  rise 6 mmHg

Adapted from K.Lee presentation 9/2005
34
Rules of Five -- 4

• Check for Compensation
• RESPIRATORY ACIDOSIS
• ACUTE Each rise in pCO2 by 10 mmHg, HCO3 should
  rise 1mEq/L
• CHRONIC Each incr pCO2 by 10 mmHg, HCO3 should
  rise 4mEq/L
• RESPIRATORY ALKALOSIS
• ACUTE Each fall in pCO2 by 10 mmHg, HCO3 should
  fall 2 mEq/L
• CHRONIC Each fall in pCO2 by 10mmHg, HCO3
  should fall 5 mEq/L

Adapted from K.Lee presentation 9/2005
35
Rules of Five -- 4

• Check for Compensation
• Compensation NEVER completely normalizes pH from
  original disorder
• If pH is normal
• mixed acid-base disorder must be present

Adapted from K.Lee presentation 9/2005
36
Rules of Five -- 5

• Calculate the Delta Gap (or 11)
• Each 1 point rise in AG above normal AG (10)
• should be accompanied by a 1 mEq/L decrease in
  HCO3
• If HCO3 is gt than predicted by 11, metabolic
  alkalosis also present
• If HCO3 is lt than predicted by 11, non-gap
  acidosis also present

Adapted from K.Lee presentation 9/2005
37
Rules of Five -- 5

• Calculate the Delta Gap (or 11) method 2
• ? Gap current AG normal AG
• current AG - 12
• ? Gap current HCO3 HCO3 before d/o
• HCO3 gt 28 pre-existing met alkalosis
• HCO3 lt 24 pre-existing non-gap acidosis

Adapted from K.Lee presentation 9/2005
38
MNEMONIC for GAP ACIDOSIS M-U-D-P-I-L-E-S

• M Methanol
• U Uremia
• D DKA or starvation ketoacidosis
• P Propylene Glycol (additive in IV benzos)
• paraldehyde rarely seen -- previous use for
  EtOH detox
• I Ingestions (Cocaine / MDMA or Ecstasy)
• INH rare, unless seizure present // Iron
  toxicity rare
• L - Lactate
• E EtOH ketoacidosis / Ethylene Glycol
• S - Salicylates

Adapted from K.Lee presentation 9/2005
39
MNEMONIC for NON-GAP ACIDOSIS D-U-R-H-A-M

• D Diarrhea (also fistula or kayexalate)
• U Ureteral Diversion (ileal conduit)
• R - RTA (renal tubular acidoses)
• H Hyperalimentation / Hypoaldosteronism
• A Acetazolamide / Aldactone
• M Miscellaneous
• toluene (glue sniffing), CaCl, MgSO4
• euvolemic DKA

Adapted from K.Lee presentation 9/2005
40
Urine Anion Gap (for NG acidosis)

• Urine anion gap aka urine net charge
• Urine Na Urine K Urine Cl UAG
• normal value mildly or zero
• cant use if urine pH gt6.5
• hyperchloremic metabolic acidosis from a
  non-renal source, NH4 production is
  appropriately increased gtgt Urine Cl ? and leads
  to (-) UAG
• Type I IV RTA renal failure, () UAG

Adapted from K.Lee presentation 9/2005
41
MKSAP Nephrology Q23 Revisited

• 63 yo factory worker presents with upper lower
  extremity diffuse muscle weakness over the past
  2 wks. For the past 6 mos, he has had low back
  pain that was sufficiently severe to cause him to
  miss work several occasions. Buffered salicylate
  tx relieved the pain somewhat.

42
MKSAP Nephrology Q23 Revisited

• Labs
• Hgb 8g/dl K 2.6meq/L
• HCT 24 Na 135meq/L
• PLT 106K/ul Cl 117meq/L
• BUN 10mg/dl Bicarb 15meq/L
• Cr 1.0mg/dl Glc 88mg/dl
• Osm 277mosmol/L Cal 11mg/dl
• ABG 7.30/31 (pCO2)
• UA neg for albumin sulfosalicylic acid

43
MKSAP Nephrology Q23 Revisited

• 135 117 10 Gluc 88
• 2.6 15 1.0 ABG 7.30 / 30 /
• U/A (-) alb / SSA
• rule1 acidemic / rule2 metabolic / rule3 AG
  3 (low)
• rule4 compensation - Yes- Bicarb15PCO2
• rule5 Delta gap is NA (only in AG acidosis)
• Thus, nongap metabolic acidosis with appropriate
  respiratory compensation. AG is LOW.hmmm

Adapted from K.Lee presentation 9/2005
44
MKSAP Nephrology Q23 Revisited

• What disease process best explains the acid-base
  disorder?
• Proximal RTA
• Salicylate toxicity- gap acidosis
• ETOH-induced lactic acidosis- gap acidosis
• Ethylene glycol toxicity- gap acidosis

45
A little more fun.

• 30 y/o M w seizure d/o previously well-controlled
  on phenytoin. After a night of partying,
• he has another seizure. In the ED
• 140 100 12 Gluc 80 EtOH 100
• 4.8 12 1.0 ABG 7.25 / 28 / 100
• U/A (-) ketones
• measured Osm 310

Adapted from K.Lee presentation 9/2005
46
A little more fun.

• 140 100 12 Gluc 80 EtOH 100
• 4.8 12 1.0 ABG 7.25 / 28 / 100
• U/A (-) ketones / meas Osm 310
• rule1 acidemic / rule2 metabolic / rule3 AG
  28
• rule4 compensation - yes, roughly fits acute
• rule5 (28-12) 12 28 (prior met. alkalosis)
• osmolal gap 0 2(140) 12/2.8 80/1.8
  100/4.6

Adapted from K.Lee presentation 9/2005
47
A little more fun.

• Methanol (EtOH screen showed just EtOH)
• Uremia (BUN/Cr wnl)
• DKA (gluc 100 negative urine ketones)
• Propylene glycol (unless his friends are
  pharmacists)
• Ingestions (UDS later returned negative)
• LACTIC ACIDOSIS
• EtOH ketoacidosis / Ethylene Glycol (no ketones)
• Salicylates (should see resp alkalosis)

Adapted from K.Lee presentation 9/2005
48
A little more fun.

• Which of the following is the most appropriate
  treatment?
• observation repeat lytes / ABG in 1 hr
• NaHCO3 100 mEq IVP
• D5W w/ 150 mEq NaHCO3/L over 3 hrs
• Hemodialysis
• Fomepizole or EtOH gtt Hemodialysis

Adapted from K.Lee presentation 9/2005
49
A little more fun.

• Which of the following is the most appropriate
  treatment?
• observation repeat lytes / ABG in 1 hr
• NaHCO3 100 mEq IVP
• D5W w/ 150 mEq NaHCO3/L over 3 hrs
• Hemodialysis
• Fomepizole or EtOH gtt Hemodialysis

Adapted from K.Lee presentation 9/2005
50
Lowering the Threshold

• What if his EtOH level 0 (osmolal gap now 22)
• and urine with rbcs rectangular crystals?
• Methanol
• Isopropyl Alcohol
• Ethylene Glycol
• Cyanide

Adapted from K.Lee presentation 9/2005
51
A little more fun.

• What if his EtOH level 0 (osmolal gap now 22)
• and urine with rbcs rectangular crystals?
• Methanol
• -gtFormaldehyde formic acid
• Isopropyl Alcohol
• ?osmolal gap (ketosis)
• w/o gap acidosis
• Ethylene Glycol
• Glycolic acid Ca ox crystal
• Positive Osmolar gap
• Cyanide
• lactic acidosis

Calcium Oxalate Crystals
Fluoresce under Woods Lamp
Adapted from K.Lee presentation 9/2005
52
MKSAP Nephrology Q46

• 43 yo woman presents with back pain and is
  evaluated for renal insufficiency. Infection with
  HIV was dx 2 yrs ago, and the patient began
  taking active antiretroviral tx with zidovudine,
  lamivudine, indinavir 1 yr later because of
  decreasing CD4 count development of oral
  candidiasis. Six mos ago, she developed fasting
  hyperglycemia and hypercholesterolemia and was
  treated with rosiglitazone and atorvastatin.

53
MKSAP Nephrology Q46

• Exam BP 130/85, HRRR, RR is 18/min, temp is
  37.8, no orthostatic changes. No JVD or HJR. The
  cardiac, pulmonary, abdominal examinations are
  normal, but 2 LE edema is noted.
• Labs
• BUN 22mg/dl K 6.0meq/L
• Na 141meq/L Cr 3.2 mg/dl
• Cl 101meq/L Cal 7.2mg/dl
• Bicarb 19meq/L PO4 9.0mg/dl
• Uric acid 9.0mg/dl Cholesterol 177mg/dl
• FBS and AIC elevated. HCT 31, MCV elevated. WBC
  3300/ul, PLT normal.
• UA protein TR, 2hematuria, No ketones, no
  glucose. Muddy brown casts and tubular epithelial
  cells seen. No crystals or erythrocytes.

54
MKSAP Nephrology Q46

• What is the most probable dx?
• Rhabdo caused by atorvastatin
• Indinavir nephrolithiasis
• Indinavir tubulointerstitial renal disease and
  atrophy
• HIV-associated nephropathy
• Diabetic nephropathy

55
MKSAP Nephrology Q46

• Exam BP 130/85, HRRR, RR is 18/min, temp is
  37.8, no orthostatic changes. No JVD or HJR. The
  cardiac, pulmonary, abdominal examinations are
  normal, but 2 LE edema is noted.
• Labs
• BUN 22mg/dl K 6.0meq/L
• Na 141meq/L Cr 3.2 mg/dl
• Cl 101meq/L Cal 7.2mg/dl
• Bicarb 19meq/L PO4 9.0mg/dl
• Uric acid 9.0mg/dl Cholesterol 177mg/dl
• FBS and AIC elevated. HCT 31, MCV elevated. WBC
  3300/ul, PLT normal.
• UA protein TR, 2hematuria, No ketones, no
  glucose. Muddy brown casts and tubular epithelial
  cells seen. No crystals or erythrocytes.

56
Renal Tubular Acidosis

• TYPE K HCO3 Urine pH Features
• I ? lt15 gt 5.3 Stones / Sjogrens
• II avg 15 lt 5.3 Glucosuria / Myeloma
• IV ? gt15 usually Low Urine K
• lt 5.3 DM HIV

Adapted from K.Lee presentation 9/2005
57
COMPLEMENT LEVELS
Adapted from K.Lee presentation 9/2005