Myoglobinuria

Characterization of myoglobin toxicity in renal cortical slices from Fischer 344 rats

Rhabdomyolysis is associated with acute renal failure. The following study first characterized myoglobin in vitro toxicity using renal cortical slices isolated from male Fischer 344 rats. This model provided interaction between various cells within the nephron and provides myoglobin access predominantly through the basolateral membrane. Second, this study examined the effect of deferoxamine (DFX) and glutathione on myoglobin toxicity to determine the role of radicals and iron. Renal cortical slices were incubated for 30-120 min with 0, 4, 10 or 12 mg/ml myoglobin. Myoglobin was pretreated with 4 mM ascorbic acid prior to addition to the slices to ensure that myoglobin was in its reduced state. In other experiments tissues were pretreated for 15 min with 0.1 mM of the iron chelator DFX or 30 min with 1 mM glutathione prior to co-incubation with myoglobin. Finally, slices were pretreated with 1 mM glutathione for 30 min, rinsed and incubated only with myoglobin. Early event changes occurred within a 60 min exposure and included a decline in pyruvate-stimulated gluconeogenesis, increased lipid peroxidation levels and decreased glutathione levels. Loss of ATP levels and increased lactate dehydrogenase (LDH) release required a 120 min exposure to myoglobin. DFX reduced myoglobin induced effects on LDH leakage but had no effect on gluconeogenesis suggesting that myoglobin toxicity had an iron dependent (LDH) and independent (gluconeogenesis) pathway. Pretreatment with glutathione provided complete protection and was mediated by intracellular events.

Rhabdomyolysis associated with gemfibrozil-colchicine therapy

OBJECTIVE

To report a case of rhabdomyolysis possibly due to combination therapy with colchicine and gemfibrozil.

CASE SUMMARY

A 40-year-old man with amyloidosis and hepatitis B virus-related chronic liver disease was admitted to the university hospital because of fatigue, lack of appetite, dark brownish urine, and myalgia for 2 weeks. The patient was receiving colchicine and gemfibrozil. Elevations of serum creatine kinase, lactate dehydrogenase, and aspartate aminotransferase concentrations with myalgia were compatible with the diagnosis of rhabdomyolysis.

DISCUSSION

To our knowledge, myopathy and rhabdomyolysis due to a combination of colchicine and gemfibrozil therapy have not been previously reported. Preexisting mild renal failure, hepatitis B-related chronic liver disease, and amyloidosis may be contributing risk factors for the development of rhabdomyolysis in this patient. An objective causality assessment revealed that the adverse drug event was possible.

CONCLUSIONS

Patients receiving combination therapy with colchicine and gemfibrozil, especially those with renal and hepatic dysfunction, should be monitored for rhabdomyolysis, and concomitant colchicine and gemfibrozil therapy should be considered in the differential diagnosis of rhabdomyolysis.

The effect of externally applied subatmospheric pressure on serum myoglobin levels after a prolonged crush/ischemia injury

BACKGROUND

Patients with injuries that cause significant muscle death often develop rhabdomyolysis. The subsequent release and entry of myoglobin into the systemic circulation leads to myoglobinuria, renal injury, and potentially acute renal failure.

METHODS

Large (5 kg) adult rabbits (n = 8) were anesthetized and a 15-kg weight placed on the posterior compartment for 4 hours. After this time, the weight was removed and releasing incisions were made. Subatmospheric pressure (125 mm Hg) was continuously applied to the wounds of four rabbits. Systemic serum samples were obtained at the time of weight removal and at 2, 4, and 8 hours postremoval, and were analyzed for myoglobin content.

RESULTS

Serum myoglobin levels were similar for both groups at the time of weight removal. Serum myoglobin levels demonstrated a progressive increase with time in nontreated animals, and were significantly elevated compared with subatmospheric pressure-treated animals at all time points (p < 0.001).

CONCLUSION

This study shows that application of subatmospheric pressure to an affected body part is associated with lower serum myoglobin levels.

Gluteal Compartment Syndrome and Sciatica after Bone Marrow Biopsy: A Case Report and Review of the Literature

The gluteal region is not commonly thought of as a compartment, yet nondistensible osseofascial boundaries do exist. As with any case of compartment syndrome expedient therapeutic measures are critical to salvaging neuromuscular function. The gluteal compartment is unique, however, because of its tremendous muscle mass and great potential for producing devastating systemic sequelae. Gluteal compartment syndrome is most commonly associated with unconscious patients who are recumbent for prolonged periods, but trauma, spontaneous bleeding, and overexertion can also cause it. We present a case report of gluteal compartment syndrome after bone marrow biopsy of the iliac crest. Recognizing gluteal compartment syndrome as an entity and maintaining a high index of suspicion for its development especially in unconscious patients can avert disaster regardless of etiology.

Laboratory diagnosis of metabolic myopathies

The metabolic myopathies are a heterogeneous group of disorders inherited by a variety of modes that include gene defects in both the nuclear and mitochondrial genomes. Many factors impact on the expression of the pathogenic mutations that cause these disorders including genetic background, environmental factors, and coexisting disorders. Molecular technology has greatly improved the ability to make definitive diagnoses in many of the metabolic myopathies in the last decade and particularly has demonstrated that the wide diversity in the severity of mutations contributes to understanding genotype-phenotype correlations. In some cases, molecular testing obviates the necessity to perform an invasive muscle biopsy. However, it is also clear that the diagnostic yield from molecular testing is incomplete and particularly low among the mitochondrial myopathies as a group, ranging from approximately 6% to 19% in well-classified high-risk groups. Therefore, it is often essential to combine clinical, biochemical, histopathologic, and molecular data for each patient in order to arrive at a definitive diagnosis. The approach to the laboratory diagnosis of metabolic myopathies is described emphasizing both noninvasive and invasive testing, highlighting the molecular methodologies with the benefits and disadvantages of each technology, and documenting how to determine whether patients have coexisting disorders.

Rhabdomyolysis: a review

Rhabdomyolysis, a syndrome of skeletal muscle breakdown with leakage of muscle contents, is frequently accompanied by myoglobinuria, and if sufficiently severe, acute renal failure with potentially life-threatening metabolic derangements may ensue. A diverse spectrum of inherited and acquired disorders affecting muscle membranes, membrane ion channels, and muscle energy supply causes rhabdomyolysis. Common final pathophysiological mechanisms among these causes of rhabdomyolysis include an uncontrolled rise in free intracellular calcium and activation of calcium-dependent proteases, which lead to destruction of myofibrils and lysosomal digestion of muscle fiber contents. Recent advances in molecular genetics and muscle enzyme histochemistry may enable a specific metabolic diagnosis in many patients with idiopathic recurrent rhabdomyolysis.

Absence of myoglobinuria in acute psychotic patients with marked elevation in serum creatine phosphokinase level

Elevated levels of serum creatine phosphokinase, muscular type (CK(MM)) are caused primarily by diseased muscle fiber. Acute psychoses are often associated with a marked increase in serum CK(MM) levels, though the reason remains obscure. Since striated muscle damage is also associated with pigmenturia and myoglobinuria, we sought to determine whether the markedly high serum CK level of acute psychosis reflects skeletal muscle damage by evaluating urinary myoglobin in affected patients. Baseline serum CK was measured on admission in 713 consecutive acute psychotic inpatients (BPRS> or =40). Those showing a serum CK levels above 1000 IU/l on the first 2 days of hospitalization underwent urine collection for myoglobin testing. Patients with physical trauma or medical conditions known to cause CKemia were excluded. Twenty-five patients were eligible for the study. In no case did myoglobinuria or pigmenturia accompany the marked CKemia. There is an unexpected dissociation between the robust increase in the serum CK(MM) levels and the absence of myoglobinuria in acute psychosis. Our negative finding may indicate that the serum CK threshold for myoglobinuria is very high (above 10000 IU/l). Alternatively, psychosis-associated CKemia may be related to an unknown, nontraumatic, pathophysiological mechanism(s).