Potassium, Blood is a topic covered in the Davis's Lab & Diagnostic Tests.

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Serum K+.

Common Use:
To evaluate fluid and electrolyte balance related to potassium levels toward diagnosing disorders such as acidosis, renal failure, dehydration, and monitor the effectiveness of therapeutic interventions.

Serum collected in a gold-, red-, or red/gray-top tube. Plasma collected in green-top (heparin) tube is also acceptable.

Normal Findings:
(Method: Ion-selective electrode)

SerumConventional & SI Units
Birth–7 d3.2–5.5 mEq/L or mmol/L
8 d–1 mo3.4–6 mEq/L or mmol/L
1–5 mo3.5–5.6 mEq/L or mmol/L
6 mo–1 yr3.5–6.1 mEq/L or mmol/L
2–19 yr3.8–5.1 mEq/L or mmol/L
Adult–older adult3.5–5.3 mEq/L or mmol/L
Note: Value ranges may vary depending on the laboratory. Serum values are 0.1 mmol/L higher than plasma values, and reference ranges should be adjusted accordingly. It is important that serial measurements be collected using the same type of collection container to reduce variability of results from collection to collection.Older adults are at risk for hyperkalemia due to the decline in aldosterone levels, decline in kidney function, and effects of commonly prescribed medications that inhibit the renin-angiotensin-aldosterone system.

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