Compare conditions

Put any two — or three — conditions side by side, adult or pediatric, to spot the look-alike differences fast, row by row.

Rhabdomyolysis

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In one line

·Muscle cells have broken open and are dumping their insides — myoglobin (the oxygen-carrying protein in muscle), potassium, phosphate, and creatine kinase (CK, an enzyme) — into the bloodstream.

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Normal physiology

·Muscle cells are wrapped in a thin, tough skin called the sarcolemma that keeps all the cell's contents — myoglobin (the oxygen-carrier), potassium, phosphate, calcium, and enzymes like creatine kinase (CK) — locked inside. The kidneys have tiny filters (glomeruli and tubules) that can handle small amounts of myoglobin and flush it out in urine. Keep that picture in your head, because the weird findings in rhabdomyolysis only make sense as a change from this normal state.

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What goes wrong

·The sarcolemma (the muscle cell's wrapper) tears open, and the cell's insides pour out into the blood and tissue spaces. Usually one upstream cause — trauma, crush injury, being stuck in one position too long (like a fall or coma), a seizure, extreme exercise, statin drugs, alcohol, street drugs (cocaine, heroin, amphetamines), severe heat (hyperthermia) or cold (hypothermia), an electrolyte imbalance (very low potassium or phosphate), or compartment syndrome (pressure building up and choking off blood flow inside a muscle compartment) — explains why the sarcolemma failed. That single broken thing upstream causes all the weird findings you see downstream.

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Hallmark signs

·Muscle pain and tenderness (myalgia)
·Muscle weakness
·Dark tea-colored or cola-colored urine
·Swollen, firm muscles
·Nausea and vomiting
·Confusion or agitation
·Decreased urine output or no urine at all
·Fever

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Red flags · escalate now

·Dark or tea-colored urine (sign that myoglobin is spilling into the urine and may be damaging the kidneys)
·Little or no urine output (sign the kidneys are failing)
·Severe muscle pain, swelling, or weakness that keeps getting worse (risk of compartment syndrome — pressure building up so high it cuts off blood flow)
·Confusion, irregular heartbeat, or chest pain (sign that potassium or calcium is dangerously out of balance and threatening the heart)
·History of a major trigger: crush injury, prolonged immobilization, seizures, extreme exercise, heat stroke, or certain drugs (statins, cocaine, amphetamines)

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Workup

·Creatine kinase (CK) level
·Serum potassium
·Serum creatinine and blood urea nitrogen (BUN)
·Urinalysis with microscopy
·Serum calcium
·Serum phosphate
·Electrocardiogram (EKG)
·Urine output monitoring

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Treatment

·Aggressive IV fluid resuscitation with normal saline, starting at 1 to 1.5 liters per hour and adjusting to keep urine output at 200 to 300 mL/hour
·Treat high potassium (hyperkalemia) with insulin plus dextrose (to shift potassium into cells), calcium gluconate (to protect the heart if the EKG shows changes), sodium bicarbonate (to shift potassium), or potassium binders like sodium polystyrene sulfonate or patiromer
·Start dialysis (hemodialysis or continuous renal replacement therapy) if the kidneys fail, potassium stays dangerously high despite treatment, the patient is overloaded with fluid and at risk for lung swelling, or severe acid or phosphate buildup happens
·Find and treat the underlying cause—stop the statin or other muscle-toxic drug, cool down the overheated patient, stop the seizure, release the crushed limb, manage the drug overdose or withdrawal, or treat the infection
·Surgical fasciotomy (cutting open the tight tissue wrapping around a muscle compartment) if compartment pressure stays above 30 mmHg despite fluids and threatens to cut off blood flow and kill more muscle
·Give calcium gluconate for low calcium (hypocalcemia) only if the patient has symptoms like muscle cramps, tingling around the mouth, or seizures; avoid giving calcium routinely
·Consider alkalinizing the urine with sodium bicarbonate (targeting urine pH above 6.5) in select cases, though evidence is mixed and it is no longer routine in all guidelines

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NCLEX trap

·Dark urine + high CK + muscle pain = think rhabdomyolysis first. The dark urine is myoglobin (a protein released from dying muscle cells), not infection. In rhabdomyolysis, the kidney is at risk because myoglobin clogs the tiny tubes inside the kidney where urine is made, not because bacteria are attacking.
·In rhabdomyolysis, low calcium is expected because calcium rushes into the dying muscle and gets trapped there. Giving calcium IV pushes more calcium into that damaged muscle and can make things worse. Only give calcium if the patient has serious symptoms like muscle twitching, seizures, or a dangerous heart rhythm—not just because the number is low.
·In rhabdomyolysis, the dipstick turns positive because myoglobin (the protein leaking from dead muscle) looks like blood to the test strip. When you actually look at the urine under a microscope, you see zero red blood cells. The myoglobin came from muscle, not from bleeding in the bladder or kidneys.
·In rhabdomyolysis, high potassium is a silent emergency. Potassium can stop the heart suddenly without any warning signs the patient can feel. Treat it immediately—get an EKG to check the heart's rhythm, give calcium gluconate (to shield the heart), insulin with glucose (to push potassium back into cells), and prepare for dialysis if needed. Never wait for symptoms.
·In rhabdomyolysis, CK rises over hours and can climb to 50,000 or even 100,000. A CK of 500 early on does not mean the damage is mild—it means you caught it early. If the patient has dark urine, muscle pain, and a crush or strain history, assume severe rhabdomyolysis is coming and start aggressive IV fluids right now (at least 200–400 mL per hour, often much more). Recheck the CK in a few hours.
·In rhabdomyolysis, kidney injury happens after the myoglobin wave hits the kidney. Normal creatinine now does not mean it will stay normal. Myoglobin clogs the kidney's tiny filtering tubes over the next several hours. Aggressive IV fluids (often 200–400 mL/hour or more, guided by urine output) are the single most important treatment—they dilute the myoglobin and flush it out before it can clog the kidney. Start fluids immediately, before the kidney numbers rise.

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