We present the case of an eight-month-old female patient admitted for a seven-day course of symptoms consisting of fever up to 40oC, refusal of food intake and vomiting. She had no family or personal pathological history of interest, and no known allergies. Physical examination revealed only small rounded laterocervical lymphadenopathies and pharyngeal hyperemia.
In the complementary study requested, he had a haemogram with normal erythrocyte sedimentation rate; C-reactive protein, 4.48 mg/dl; and normal sodium, potassium, chloride, magnesium, calcium (Ca), phosphorus (P), bilirubin, protein and blood gases. Blood, urine and stool cultures were negative and a pharyngeal swab isolated Parainfuenzavirus 3.
An analytical finding that attracted attention was an AF level of 5252 IU/l. The parents were again asked about the cause of this elevated AF, with particular emphasis on the consumption of drugs, history of fractures or previous illnesses, both in the patient and in her relatives, but no new data were obtained.
A new determination of AF was requested to check that it was not a laboratory error, as well as GGT, vitamin D, parathyroid hormone (PTH) and AF isoenzymes. This analysis confirmed elevated AF (6070 IU/l), with the rest of the requested parameters (GGT, AF isoenzymes, vitamin D and PTH) being normal.
On the seventh day of admission, once the febrile process had resolved, the patient was discharged with a diagnosis of Parainfuenzavirus 3 infection and hyperphosphataemia under study. He was monitored clinically and with periodic AF tests in outpatient clinics.
Subsequent controls showed a progressive decrease in AF, she remained asymptomatic and with a strictly normal physical examination, so she was definitively discharged after six months, after presenting two AF determinations within normal values for her age, with the diagnosis of transient benign hyperphosphataemia of infancy (HTBI).