Appeal type: Medical necessity
Decision: Upheld

Diagnosis: muscle injury (rhabdomyolysis).
Treatment: Inpatient Hospital Stay.
The insurer denied the Inpatient Hospital Stay.
The determination is upheld.

The patient with an unremarkable medical history was taken to the emergency department (ED) because of bilateral calf pain and difficulty walking. She had been diagnosed with gastroenteritis the week before and was still on antibiotics. There was no history of trauma, no fever, and no prior episodes. Vital signs included a temperature of 97.1 degrees Fahrenheit, heart rate 109, respiratory rate 20. Examination was significant for no acute distress, moist mucous membranes, clear lungs, regular heart rate, benign abdomen, no joint swelling, limited range of motion of the bilateral lower extremities due to pain, no swelling or erythema, and good strength and tone. X-rays were unremarkable. Laboratory evaluation was significant for a white blood cell count (WBC) count of 7.3 thousand (K), potassium 4.2, blood urea nitrogen (BUN) 13.0, creatinine 0.5, lactate 0.7, aspartate aminotransferase (AST) 422, alanine aminotransferase (ALT) 585, creatine kinase 2216. A respiratory viral panel was pending.
She was treated with a normal saline bolus and Motrin prior to admission for further management. She was given a second intravenous (IV) fluid bolus prior to leaving the ED. Full admission was requested for management of rhabdomyolysis. Admission orders included vital signs every four hours, regular diet for age, IV fluids at maintenance and a half, repeat creatine kinase (CK) and comprehensive metabolic panel (CMP), urinalysis. The viral panel returned positive for influenza A. She did well overnight, able to ambulate with decreased muscle pain. A repeat CK was 1893. The BUN decreased to 6, a urinalysis was unremarkable. Treatment with oseltamivir had been initiated. She remained on intravenous (IV) fluid hydration. She continued to improve, with minimal pain, tolerating a regular diet, voiding at baseline. The CK was down to 1180. She was deemed stable for discharge to follow-up in two to three days with her pediatrician.
At issue is the medical necessity of an inpatient stay.
An inpatient stay was not medically necessary. Rhabdomyolysis is generally defined as an elevation of serum creatine kinase activity at least ten times the upper limit of normal followed by rapid decrease to normal. It occurs when skeletal muscle is broken down, releasing electrolytes and myoglobin into the circulation. Rhabdomyolysis may be caused by substance abuse, medications, trauma, or seizures. It may also be virus-associated, with the most common virus being influenza. Clinical findings include myalgia, weakness, and pigmenturia, but less than 10% of patients present with this triad. The most concerning complication is acute kidney injury, although arrhythmias from electrolyte abnormalities also are a source of morbidity. Acute renal failure may occur as a result of acute tubular necrosis when myoglobin causes obstruction in the kidney. This typically occurs with creatine kinase (CK) (creatine phosphokinase (CPK)) levels greater than 16,000. Initial treatment is aimed at preserving renal function, managing electrolyte derangements, and aggressively maintaining hydration. 
While influenza is typically associated with pulmonary symptoms and sequelae it has also been associated with myocardial infarction, pericarditis, Guillain-Barre syndrome, encephalitis, and potentially severe rhabdomyolysis. Myalgia is a typical complaint for patients with influenza, but acute myositis and rhabdomyolysis occur as well, more often in children than in adults. Treatment of rhabdomyolysis in this circumstance is aimed at preventing acute renal failure.
This young female child presented with bilateral calf pain, and was found to have an elevated CK. She was treated with IV fluids and oseltamivir for influenza A, with significant improvement in pain. She had no issues with voiding for the duration of her hospital stay. While it was reasonable to monitor this child in the hospital setting for improvement versus worsening of her condition, she was overall hemodynamically stable with good urine output, no evidence of acute renal failure or acute kidney injury, and no other significant sequelae from influenza A infection. She did not require acute inpatient admission and could have been safely managed at a lower level of care.