A case of hyperkalaemia associated with hypocalcaemia

Area of Science:

• Clinical Biochemistry
• Internal Medicine
• Laboratory Medicine

Background:

• Electrolyte imbalances, such as hyponatremia, hyperkalemia, and hypocalcemia, can present with non-specific symptoms like lethargy and anorexia.
• Accurate biochemical analysis is critical for diagnosing and managing these electrolyte disturbances.

Observation:

• An elderly patient presented with lethargy and anorexia, showing initial biochemical results of mild hyponatremia, moderate hyperkalemia, and severe hypocalcemia.
• Despite severe hypocalcemia, the patient lacked typical clinical manifestations, and electrocardiogram findings did not support hyperkalemia or hypocalcemia.

Findings:

• Repeated biochemical tests revealed hyponatremia with associated hypokalemia and normocalcemia, contradicting initial findings.
• The discrepancy suggested pseudohyperkalemia and pseudohypocalcemia, likely due to contamination with potassium ethylenediaminetetraacetic acid (K2EDTA) from blood collection tubes.

Implications:

• Contamination of blood samples, particularly with K2EDTA, can lead to erroneous electrolyte measurements, mimicking true hyperkalemia and hypocalcemia.
• Implementing proper blood collection protocols, such as drawing serum gel tubes first, is essential to prevent sample contamination and ensure diagnostic accuracy.