1) showed an albumin of 64.4% and normal A/G ratio, which suggests spurious hyperproteinemia
. The patient was being treated with dextran (1).
The basic principle of potentiometry is the same in both methods, but the indirect method uses an assumption that makes its use flawed under conditions of hyperlipidemia or hyperproteinemia
.11 If one considers that the absolute amount of sodium in such cases (ie, in a smaller fraction of serum water) is decreased, then any dilution by a fixed amount will introduce a dilution error, which results in a decrease in measured sodium.
Uncommon causes include polycythemia vera, emphysema, sickle cell disease, multiple myeloma, macroglobulinemia, hyperproteinemia
, cystic fibrosis of the pancreas, and peritoneal dialysis.
The marriage of blood gases and electrolytes on a single specimen has led to a standard turnaround time of no greater than 5 to 10 minutes for whole blood tests.[1,2] Using whole blood permits direct measurement not only of blood gases and pH but also of ionized calcium, ionized magnesium, glucose, and other analytes with activity-based ion-selective electrodes (ISEs) and substrate-specific electrodes (SSEs). Artifacts due to hyperlipidemia and hyperproteinemia
are thus eliminated and clinical accuracy is improved. Whole blood instruments that cannot perform activity-based measurements quickly and directly on anaerobically processed specimens lack these advantages; therefore, they generally are not intended for critical care settings, where rapid response is imperative.
Serum chemistry abnormalities will include hyperproteinemia
, hyperglobulinemia, hypoalbuminemia and elevated alanine aminotransferase and alkaline phosphatase activities.
The low sodium concentration was found to be a result of pseudohyponatremia, an artificially low measurement of sodium concentration produced by the presence of severe hyperproteinemia
Results of blood tests done by the referring veterinarian showed mild leukocytosis, hypercalcemia, hyperproteinemia
, and high levels of triglycerides, consistent with egg-laying.
Serum immunoelectrophoresis did not reveal hyperproteinemia
Evaluation of bias is performed for lipemia (triglycerides 3000 mg/dL or 33.9 mmol/L), hemolysis (hemoglobin 500 mg/dL), icterus (bilirubin 20 mg/dL or 342 [micro]mol/L), and hyperproteinemia
(total protein 12 g/dL).
The mild hyperproteinemia
and mild hypercalcemia were likely associated with hemoconcentration caused by dehydration.
Pseudohyponatremia, a laboratory artifact, can be caused by hyperlipidemia and hyperproteinemia
, which displaces water to produce falsely low sodium values when it is measured with indirect diluted ion-selective electrode methods (3).
(1) Abnormalities noted in the plasma biochemical analysis were hyperproteinemia
(6.6 g/dL [reference interval, 2.8-4.6 g/dL]), hypercalcemia (9.7 mg/dL [reference interval, 7.3-9.1 mg/dL)], high uric acid concentration (25 mg/dL [reference interval, 6.6-19 mg/dL]), and hyperphosphatemia (9.3 mg/dL [reference interval, 2.5-6.1 mg/dL]).