Spurious hypophosphatemia in a patient with multiple myeloma.
We report a patient with multiple myeloma and a prolonged history of hypophosphatemia who had remained asymptomatic. Extensive evaluation for a cause, including the search for a renal tubular disorder, oncogenous osteomalacia, or a parathyroid hormone (PTH)-related protein was unproductive. Renal biopsy showed no evidence of myeloma kidney. Subsequent mixing of the immunoglobulin G (IgG) fraction from the patient's serum with normal human serum, confirmed that the observed hypophosphatemia was spurious, resulting from interference of large amounts of an abnormal IgG with a standard automated laboratory assay for phosphate.
Loghman-Adham
M
M
Department of Internal Medicine, University of Utah School of Medicine, Veterans Affairs Medical Center, Salt Lake City 84148, USA.
Walton
D
D
Iverius
P H
PH
Deiss
A
A
Knight
J A
JA
Cheung
A K
AK
D001322:Autoanalysis; D003951:Diagnostic Errors; D006801:Humans; D017674:Hypophosphatemia / Q000175:diagnosis*; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000097:blood / Q000150:complications*; D012004:Rectal Neoplasms / Q000150:complications
D007074:Immunoglobulin G