Hyperkalaemia: thrombocytosis elevated serum potassium.

Clinical bottom line (level 4)

  1. Patients with platelet counts above 500, were at an increased risk of having a raised potassium (NNH = 29 at unknown) .
  2. Potassium levels increased by about 0.3 mmol/l.
Graber et al: American Journal of Kidney Disease 1988; 12 (2): 116-120
Expires February 2004

The study

Case-control study with objective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: Veterans Affairs medical centre, USA

444 patients (aged ?, ?% male) elevated platelet count

Excluded if
  • known myeloproliferative disease
  • serum electrolytes measured >12 hours after platelets


    • Cases: 161 patients (% male, mean age ): elevated platelet count (>500 x 10 9 /ml)
    Controls: 283 patients (% male, mean age ): normal platelet count


    Outcomes studied:
  • hyperkalaemia

    • The evidence

    Patient expected event rate for hyperkalaemia: 1.50%
    risk factor hyperkalaemia
    present    		 hyperkalaemia
    absent    		 unadjusted OR
    (95% CI)    		 NNH
    (95% CI)
    thrombocytosis 55 106 3.43
    (2.13 to 5.54)     		29
    (16 to 62)
    no thrombocytosis 36 138

    Comments

    1. A correlation between increasing platelet count and increasing potassium levels was noted (r=0.31, p<0.001).
    2. mean difference in potassium between patients with high and normal platelet counts was 0.26 mmol/l (95% CI: 0.26 to 0.26).
    3. On review of 50 charts of patients with elevated platelet counts, no cause for raised potassium levels could be found. This is a poor evaluation, being unblinded and incomplete. Uncertain how many patients had true hyperkalaemia.
    4. No significant correlation between haemocrit, bicarbonate or creatinine and potassium level or platelet count.

    Citation

    1. Graber M, Subramani K, Corish D, et al: Thrombocytosis elevates serum potassium. American Journal of Kidney Disease 1988; 12 (2): 116-120
    Contributor: Chris Ball and Clare Wotton, February 2000
    Reviewer:

    Clinical Question.
    Patient patients
    Intervention or Exposure elevated platelet count
    Comparison normal platelet count
    Outcome hyperkalaemia