Nephrology Case Presentation

Douglas Stahura DO

17 September 2002

“Set the appropriate learning environment”

Learning Objectives

Rhabdomyolysis– Definition– Acute renal failure– Pathophysiology– Clinical presentation– Treatment– Case studies

Case 1

56 y/o CF presented with Acute MI, developed pulseless right lower extremity. Normal renal function.

Case 2

48 y/o CM found “down” after 3 days in his kitchen. Unresponsive, hypotensive, anuric.

Na 185, Glucose 2500, CPK 18,000

Case 3

62 y/o “gentleman” found by police in park unresponsive and smelling of alcohol.

Thin, cachetic, hypotensive. Bun 22, Creatinine = 7.6, CPK=22,000

Case 4

19 y/o AAF presents with weakness and falls. 3rd ED visit in 7 weeks.

K=2.8, CPK=19,000, BUN=55, Creatinine=6.2

Case 5

18 y/o CM presents by squad from local arena where “The Who” reunion tour kicked off. “Festival seating” caused a rush at the gate.

Pt has extensive bruising and crush injuries.

Case 6

Earthquake levels 4 story apartment building trapping 18 people. The injured present to trauma stations from 1 to 30 hours after the collapse.

Case 7

76 y/o AAM presents with nausea and anorexia x2 weeks. Now feels week. Dark urine.

PMH: CAD, DM2, HTN BUN=110, creatinine=8.2, CPK 42,000

Case 8

27 y/o Air Force Captain presents on Monday with red discolored urine that started Sunday.

Case 9

17 y/o AAF presents from home by EMS in seizure. Further efforts require 90 minutes to gain control of her convulsions.

Case Studies

All the above cases were complicated by acute renal failure induced by endogenous toxicity to myoglobin released by damage to muscle cells – rhabdomyolysis

Definition

Rhabdomyolysis– Muscle necrosis– Release of intracellular constituents of muscle cells

Severity– Asymptomatic enzyme elevation– Life threatening enzyme elevation, electrolyte

disturbances, acute renal failure

Myoglobinuric Acute Renal Failure

Classic description from 1941 when Bywaters described “crush syndrome” in which victims of the London Blitz trapped and crushed in bombed buildings would, despite rescue, die of uremia soon afterwards

Myoglobinuric Acute Renal Failure

Myoglobin – heme containing protein – Freely filtered at the glomerulus

Proximal endocytic reabsorption is overwhelmed

Delivery to distal tubule is increased

Myoglobinuric Acute Renal Failure

Acute Tubular Necrosis (ATN) is provoked– Intrarenal vasoconstriction by scavenging NO– Third spacing of fluids leads to hypovolemia– Obstructing tubular casts, especially in acidic urine– Iron may be directly toxic

Trauma Crush, Burn, Electric shock

Ischemia Vascular occlusion, compression,substance abuse (EtOH, heroin)

Exercise Marathon, convulsions

Metabolic Hypokalemia, Hypophosphatemia

Infection Hyperthermia, virus, bacterial

Drugs Fibrates, HMG CoA reductase inhibitors

Inflammatory Polymyositis

Genetic McArdle’s , PFK-1 deficiency, carnitine palmityl transferase deficiency

Clinical Findings

Muscle pain is variable Urinalysis

– Dipstick strongly positive for blood– Few if any RBC’s on microscopic– Color may be red-brown-black

CPK elevated– General correlation of CPK with ARF (>16,000)

Clinical Findings

Creatinine– Serum levels high out of proportion to BUN

Electrolytes– Potassium, Uric acid, Lactic acid, phosphorous

released by necrotic myocytes– Hypocalcemia due to calcium-phosphate

precipitation

Treatment

Fluid replacement– Saline infusion @ 1.5 L/hr

Forced diuresis +/- urinary alkalinization– Goal is suggested as 300 cc/hr– .45 NS + 10 gm Mannitol + 40 Meq NaHCO3

Treatment

Mannitol– Diuresis maintains high flow rate through tubules – Possible free radical scavenging effect

Alkalinization– May provide theoretical advantage in preventing

conversion of myoglobin to methemoglobin– May cause precipitation of calcium phosphate in

urinary system

Treatment

Role of acute dialysis– Does not remove myoglobin– May be needed to control the severity of

hyperkalemia– CVVHDF may not be able to manage

Case 1

56 y/o CF presented with Acute MI, developed pulseless right lower extremity. Normal renal function.

Pt has occluded aorto-bifem bypass, pulseless, cold, pale-to-blue, painful leg.

Case 2

48 y/o CM found “down” after 3 days in his kitchen. Unresponsive, hypotensive, anuric.

Na 185, Glucose 2500, CPK 18,000 Pt lay on the floor in his kitchen >72 hours in

one position. Has muscle breakdown on right side of head, shoulder, arm, hip leg.

Case 3

62 y/o “gentleman” found by police in park unresponsive and smelling of alcohol.

Thin, cachetic, hypotensive. Bun 22, Creatinine = 7.6, CPK=22,000

Chronic alcoholics have pre-existing hypophosphatemia– Increased renal losses, damage to proximal epi– Decreased GI intake/absorption– Muscle depletion of phosphorous

Case 3

Superimposed second metabolic insult result in hypophosphatemic rhabdo (ATP theory)

Respiratory alkalosis – prolonged intense hyperventilation as seen with EtOH withdrawal– Increase in pH activates glycolysis increasing

phosphorylated compounds within the cell. Serum phosphorous falls precipitously

Case 4

19 y/o AAF presents with weakness and falls. 3rd ED visit in 7 weeks.

K=2.8, CPK=19,000, BUN=55, Creatinine=6.2 Hypokalemic periodic paralysis can be

associated with hypophosphatemia.

Case 5

18 y/o CM presents by squad from local arena where “The Who” reunion tour kicked off. “Festival seating” caused a rush at the gate.

Pt has extensive bruising and crush injuries. Classic crush syndrome, can be associated

with compartment syndrome

Case 6

Earthquake levels 4 story apartment building trapping 18 people. The injured present to trauma stations from 1 to 30 hours after the collapse.

Classic crush syndrome Fluids initiated in the field to replete volume

and force diuresis may be of significant benefit even before a pt is freed, or crushed limb is reperfused.

Case 7

76 y/o AAM presents with nausea and anorexia x2 weeks. Now feels week. Dark urine.

PMH: CAD, DM2, HTN BUN=110, creatinine=8.2, CPK 42,000 Pt has dysmetabolic syndrome Hyperlipidemia treated with statin and fibrate

Case 8

27 y/o Air Force Captain presents on Monday with red discolored urine that started Sunday.

Previously healthy, no meds, no previous urinary complaints (hematuria/proteinuria)

You happen to remember that WPAFB held annual Air Force marathon on Saturday.

Case 9

17 y/o AAF presents from home by EMS in seizure. Further efforts require 90 minutes to gain control of her convulsions.

Intense electrical stimulation of muscles can cause rhabdo

References

Comprehesive Clinical Nephrology, Johnson, Feehally, London, UK,2000 Harrison’s Principles of Internal Medicine 14th, Fauci, New York, NY 1998 The Kidney 6th, Brenner and Rector,Philadelphia, PA 2000