Rhabdomyolysis with acute kidney injury in a case of hanging

Abstract

Although well-known as a complication of other hypoxic conditions such as near drowning, status asthmaticus and carbon monoxide poisoning, rhabdomyolysis has not been reported in patients with hanging. The authors report a case of partial hanging complicated by rhabdomyolysis and acute kidney injury.

Background

Rhabdomyolysis is an emergency condition which can arise from a multitude of aetiologies.¹ Regardless of the cause, the end result is the widespread disintegration of striated muscle, flooding the extracellular milieu with various ions and molecules that are normally restricted to the intracellular compartment, including potassium and phosphate ions and myoglobin. In turn, myoglobin can precipitate within renal tubules resulting in acute renal failure.

This case highlights rhabdomyolysis as a potential complication of hanging. It underscores the central role of hypoxia in the pathogenesis of rhabdomyolysis regardless of the mechanism by which hypoxia is produced.

Case presentation

A 32-year-old farmer with a history of low mood and insomnia was found by his sister, hanging from a tree with a nylon rope, with his feet touching the ground. He was immediately brought down and rushed to a local hospital, where he was found to be violent, sedated with diazepam and then referred to us. At presentation, he was comatose with a Glasgow coma scale of 6/15. General physical examination showed bradycardia with a normal systemic pressure. A brownish ligature mark was visible over the anterior aspect of his neck, 1.5 cm wide and 8 cm long, above the level of the thyroid cartilage (figure 1). Neurologic examination revealed bilaterally symmetrical reactive pupils, generalised hypotonia, sluggish deep tendon reflexes and bilateral flexor plantars. Other systems were normal.

Figure 1.

Ligature mark over anterior aspect of neck.

Investigations

Routine laboratory tests at admission including renal function tests were normal except for neutrophilic leukocytosis (total leucocyte count: 19 900/cu.mm, 93% neutrophils). A plain CT of the head and a cervical spine x-ray ruled out surgical injuries. He was diagnosed to have hypoxic ischaemic encephalopathy secondary to hanging and treated with parenteral dexamethasone, mannitol and the application of a hard cervical collar. The patient responded to this therapy, and his sensorium improved steadily over the next 24 h. Despite maintaining a good urine output, serial renal function tests deteriorated with serum levels of urea and creatinine peaking at 82 mg/dl and 2.5 mg/dl, respectively. Simultaneously, serum uric acid and phosphate levels rose to 10.7 mg/dl and 5.4 mg/dl, respectively. Serum creatine kinase was massively elevated (19 250 U/l). Liver function tests were also deranged (serum aspartate aminotransferase 1038 U/l, serum alanine aminotransferase 222 U/l and serum alkaline phosphatase 232 U/l). Urine tested positive for presence of myoglobin.

Differential diagnosis

• ▶Steroid induced myopathy and rhabdomyolysis
• ▶Hypoxic rhabdomyolysis.

Treatment

The patient was diagnosed to have acute kidney injury probably due to rhabdomyolysis with myoglobinuria with ischaemic hepatitis secondary to hypoxia. He was treated with intravenous fluids, sodium bicarbonate and mannitol.

Outcome and follow-up

Renal and hepatic parameters recovered steadily. He was treated for bipolar affective disorder with fluoxetine, lithium and lorazepam and discharged.

Discussion

Hypoxia is a recognised cause of rhabdomyolysis. Prolonged failure of oxygenation can result in widespread failure of the sodium-potassium adenosine triphosphatase pump² responsible for maintaining integrity of myocytes resulting in massive dissolution. This is the underlying mechanism of rhabdomyolysis in such varied conditions as near drowning,³ status asthmaticus,⁴ hydrocarbon inhalation⁵ and carbon monoxide poisoning.⁶ We propose a similar mechanism for rhabdomyolysis in hanging.

Levels of serum creatine kinase above ten times the normal upper limit⁷ like those seen in our patient are diagnostic for rhabdomyolysis, as no other conditions are known to produce such extreme creatine kinase elevations.¹ However, creatine kinase itself is non-toxic, and serves mainly as a marker for the severity of disease.⁸ Conversely, myoglobin, an oxygen storing molecule closely related to haemoglobin,⁹ plays a central role in the pathogenesis linking rhabdomyolysis with its principal complication, renal failure; yet, serum and urine levels of myoglobin are unreliable markers for rhabdomyolysis.^{10 11} This has been explained by the rapid clearance of myoglobin by hepatic metabolism.¹² We were therefore able to make a confident diagnosis of rhabdomyolysis based on serum creatine kinase levels alone.

Acute renal failure is the most important complication of rhabdomyolysis, occurring in upto 33% of patients.² Similarly, rhabdomyolysis itself is a leading cause of acute renal failure, responsible for 5–25% of all cases of renal failure.¹³ Furthermore, the risk of renal failure in a patient with rhabdomyolysis has been showed to rise progressively with higher levels of serum creatine kinase elevation.¹⁴

Once rhabdomyolysis has been diagnosed, the treatment strategy is targeted to mitigate kidney injury by preventing the precipitation of myoglobin within the renal tubules. This is achieved by flushing the kidneys with fluid, maintaining an hourly urine output of 150 to 300 ml,¹⁵ alkalinisation of the urine to a pH beyond 6.5¹⁶ to prevent dissociation of the ferrihemate moiety responsible for oxygen free-radical generation, and the judicious use of mannitol and loop diuretics.¹⁵

To conclude, this is the first reported case of rhabdomyolysis following hanging, in medical literature. An exhaustive search for previously reported cases yielded only one possible instance¹⁷; however, the patient in question was suffering from status dystonicus following hanging, which likely was the cause of his rhabdomyolysis rather than the hanging itself. Our patient never suffered convulsive symptoms at any point of his illness, making hypoxia secondary to hanging the primary cause for rhabdomyolysis.

Learning points.

• ▶Clinicians should be aware that rhabdomyolysis is a potential complication of hanging and therefore actively monitor the patient for it.
• ▶Rhabdomyolysis can occur as a delayed complication of hypoxic injury, well after hypoxia is corrected.
• ▶Prompt and appropriate management can effectively mitigate this potentially severe complication.