Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Recognise muscle breakdown before the classic triad appears, control its cause, prevent pigment-associated kidney injury and treat potassium, compartment and thermal emergencies without harmful routine adjuncts.
Pigment nephropathy is most likely when a high myoglobin burden is combined with aciduria, volume depletion and reduced renal perfusion. Myoglobin disappears from plasma and urine more rapidly than CK, so a patient can have a diagnostic CK rise after dark urine has resolved. CK magnitude helps stratify risk but cannot replace the clinical picture: even a lower value can be important in CKD, sepsis or ongoing muscle ischaemia, while a high value with prompt treatment may not lead to AKI.
The first management priority is the cause. Release a crush only within an organised rescue plan, terminate seizures, cool heat illness, stop a toxic exposure, treat infection and obtain urgent surgical assessment for compartment syndrome or threatened limb. Simultaneously check an ECG and potassium because intracellular potassium release can cause fatal arrhythmia before creatinine rises. Fluids should restore perfusion and dilute tubular pigment, but aggressive administration becomes dangerous once oliguria or lung congestion prevents excretion.
This topic crosses emergency medicine, surgery, toxicology, critical care and nephrology. Fluid composition, electrolyte protocols and any alkalinisation strategy vary locally; use the current UKKA hyperkalaemia and institutional rhabdomyolysis guidance. Drug doses here are framed as supervised pathways rather than invented precision.
Crush injury, prolonged immobilisation, limb ischaemia and compartment pressure disrupt muscle perfusion and cell membranes, often with concurrent hypovolaemia.
Extreme exertion, prolonged seizures, hyperthermia and electrical injury create intense energy failure and direct myocyte damage.
Severe infection, electrolyte disturbance and inherited metabolic susceptibility can precipitate muscle breakdown, sometimes without trauma or the classic symptom triad.
Statins, particularly with interacting medicines, recreational substances and other toxins can injure muscle; timing, overall exposure and competing causes determine attribution.
Energy depletion, mechanical disruption or toxin effects allow intracellular calcium accumulation and destructive enzyme activation within skeletal muscle.
Damaged cells release myoglobin, potassium, phosphate, urate and enzymes into the circulation, while fluid shifts into injured muscle.
Filtered myoglobin causes oxidative epithelial toxicity and combines with cellular debris to obstruct tubules, especially during hypovolaemia and acidic conditions.
Falling filtration reduces potassium and acid clearance, while shock and ongoing muscle necrosis continue generating the same dangerous solutes.
Crush injury, entrapment, prolonged unconsciousness or pressure necrosis causes swollen tender muscle and systemic pigment release. Limb neurovascular compromise or pain out of proportion raises compartment syndrome and demands urgent surgical review.
Severe exercise, heat exposure, hyperthermia, collapse or altered cognition can precede rhabdomyolysis. Heat stroke is a critical illness requiring immediate cooling and multi-organ support, not merely intravenous fluid for a high CK.
A statin interaction, stimulant, antipsychotic-associated hyperthermic syndrome, serotonin toxicity, alcohol or illicit drug exposure may be causal. Look for rigidity, autonomic features and co-ingestants rather than attributing all cases to the prescribed statin.
Dark brown urine and a strongly haem-positive dipstick with few erythrocytes support myoglobin. The pattern is time-dependent and its absence does not exclude muscle breakdown once pigment has cleared.
Rapid potassium and phosphate release, metabolic acidosis and early hypocalcaemia can occur before kidney injury is fully visible. ECG change, weakness or arrhythmia determines emergency treatment, while later rebound hypercalcaemia can complicate recovery.
Urinary erythrocytes on microscopy support bleeding, whereas strongly positive dipstick blood with few cells and muscle injury suggests myoglobinuria.
Anaemia, low haptoglobin, indirect hyperbilirubinaemia and plasma haemoglobin support haemoglobinuria rather than muscle-derived pigment in urine.
Subacute symmetrical weakness, autoimmune features and persistent muscle inflammation suggest immune myositis, though severe cases can themselves cause rhabdomyolysis.
AST may originate from damaged muscle; creatine kinase trajectory, other liver tests and the clinical context prevent mislabelling isolated rhabdomyolysis as primary hepatitis.
Rapid potassium release from muscle, compounded by renal failure and acidosis, can cause malignant arrhythmia before creatinine peaks.
Tubular toxicity, obstruction and hypoperfusion can produce severe oliguric AKI and a temporary need for renal replacement therapy.
Muscle swelling within a closed fascial space impairs perfusion and nerves, creating a limb-threatening process that further accelerates necrosis.
Calcium initially enters damaged muscle, causing hypocalcaemia, then may return during recovery and produce rebound hypercalcaemia.
Myoglobin is cleared quickly, whereas CK often peaks later. Dark urine can disappear before presentation, so a negative pigment dip does not invalidate a strongly compatible history and rising CK.
Massive muscle disruption releases potassium immediately, and arrhythmia can precede the creatinine rise used to label AKI. ECG and electrolyte testing belong at the front of the pathway.
Calcium can fall early through deposition in injured tissue and rise later as it remobilises during recovery. Treat the patient and emergency indication, not an isolated asymptomatic early value.
Compartment pressure can compromise muscle and nerves while large arteries still transmit a palpable pulse. Pain pattern, tense swelling and neurological change require surgical judgement.
A new CYP-interacting medicine, dose change, frailty, hypothyroidism or acute illness may convert tolerated therapy into toxicity. Recording the context informs safer future lipid management.
Waiting for muscle pain, weakness and dark urine together misses many cases in unconscious, elderly or critically ill patients.
Using CK alone to determine dialysis ignores the actual indications: refractory potassium, acidosis, overload, uraemic complications and overall physiology.
Driving a universal high urine-output target with fluid despite anuria or lung congestion can produce severe respiratory failure without clearing pigment.
Giving routine calcium for asymptomatic early hypocalcaemia may increase tissue calcium deposition and does not address the underlying muscle injury.
Restarting a suspected statin without reviewing interactions and the cardiovascular indication risks recurrence, while permanent unreviewed cessation loses preventable cardiovascular benefit.
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After a prolonged seizure, a patient has dark urine, a dipstick strongly positive for blood, but microscopy shows only one red cell per high-power field. What does this suggest?
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes
No fixed multi-litre target is safe for every patient. Slow or stop when oliguria, heart failure or pulmonary congestion emerges; fluid cannot clear potassium or pigment when filtration has failed.
It does not lower serum potassium. Do not give solely for an asymptomatic early low calcium in rhabdomyolysis, and verify the local choice of calcium chloride versus gluconate and access requirements.
Hypoglycaemia is common and can be delayed, especially in renal failure. This is a temporising measure, so repeat potassium and do not allow a transient fall to delay dialysis when release continues.