When multiple electrolytes are deranged, the order of correction determines success:
This tool uses the Katz/Hillier hybrid: corrected Na = measured Na + 1.6 × ((glucose − 100)/100) for glucose up to 400 mg/dL, then 2.4 per 100 mg/dL for the increment above 400. Applying the higher 2.4 factor to the entire glucose elevation (a common coding error) overestimates corrected sodium in severe HHS and can lead to inappropriate withholding of free water. The relationship is non-linear and steeper at very high glucose, which the hybrid captures.
Note: there is no single universally-mandated factor - the classic Katz value is 1.6, Hillier (1999) argued 2.4 fits better across the range, and the piecewise hybrid used here is a pragmatic middle ground.
The calcium-phosphate solubility product and its > 55 mg²/dL² threshold (KDOQI) are calibrated to total (measured) calcium × phosphate - not albumin-corrected calcium. Using corrected calcium would falsely inflate the product in hypoalbuminaemic patients and could wrongly block necessary calcium replacement. This tool therefore grades hypo/hypercalcaemia severity on corrected calcium (correct for grading) but computes the Ca×PO₄ product on measured calcium (correct for the product).
Total body potassium is depleted in every DKA patient, even when serum K looks normal or high. Insulin drives K intracellularly and can precipitate fatal hypokalaemia. Do not start insulin until K is known and confirmed above 3.3 mEq/L. This tool surfaces the DKA potassium rule whenever DKA is flagged, whether or not a potassium value has been entered.
Magnesium gate: low Mg drives renal K wasting (ROMK) and impairs PTH, so both hypokalaemia and hypocalcaemia are refractory until Mg is replaced. Potassium trap: replacing K raises serum Na (~1 mEq Na per mEq KCl); in a hyponatraemic patient this can overshoot the safe sodium limit and cause osmotic demyelination - count K replacement against the 24h sodium budget.
| Pattern | Signature | Key Action |
|---|---|---|
| Refeeding Syndrome | K↓ Mg↓ PO₄↓ | Replace all three. Thiamine before glucose. Slow Na correction (high ODS risk). |
| Tumour Lysis Syndrome | K↑ PO₄↑ Ca↓ (+ high urate, AKI) | Hydration, rasburicase. Treat hyperK. Don't give calcium for asymptomatic hypocalcaemia. |
| CKD Mineral-Bone Disease | Ca↓ PO₄↑ | Phosphate binders, calcitriol. Correct phosphate before calcium. |
| Diuretic Depletion | Na↓ K↓ Mg↓ | Hold diuretic. Mg first, then K. Volume restore for Na. |
| DKA | Total body K, Mg, PO₄ depleted; pseudo-hypoNa | No insulin if K < 3.3. Replace K/Mg/PO₄. Correct glucose - Na follows. |
| Renal Retention | K↑ Mg↑ PO₄↑ (oliguric) | Membrane stabilisation if hyperK with ECG changes. Dialysis is definitive. |
ΔNa per 1 L infusate = (Infusate Na − Serum Na) / (Total Body Water + 1). This estimates how much 1 litre of a given fluid will move the serum sodium, and is preferred over closed-system "deficit" formulas (which ignore renal free water clearance and routinely cause ODS). This panel shows the ΔNa figure as a quick reference when sodium is low and weight is entered; for the full tier-gated infusion schedule, monitoring timeline, and overcorrection-rescue protocol, open the dedicated Acute Hyponatraemia Protocol.
| Electrolyte | Normal | Low (severe) | High (severe) |
|---|---|---|---|
| Sodium | 135 - 145 mEq/L | < 120 (severe), < 110 (critical) | > 160 mEq/L |
| Potassium | 3.5 - 5.0 mEq/L | < 2.5 mEq/L | ≥ 6.5 mEq/L |
| Magnesium | 1.8 - 2.4 mg/dL | < 1.0 mg/dL | > 7.0 mg/dL |
| Calcium (corrected) | 8.5 - 10.5 mg/dL | < 6.0 mg/dL | > 14 mg/dL |
| Phosphate | 2.5 - 4.5 mg/dL | < 1.0 mg/dL | > 7.0 mg/dL |
Corrected Ca = measured Ca + 0.8 × (4.0 − albumin), used for severity grading. Mg: 1.8 to 2.4 mg/dL ≈ 0.75 to 1.0 mmol/L (divide mg/dL by 2.43). Phosphate: divide mg/dL by 3.1 for mmol/L.
AMA Style:
Umakanth S. Comprehensive Electrolyte Panel. MEDiscuss. Published 2026. Accessed .
Vancouver Style:
Umakanth S. Comprehensive Electrolyte Panel [Internet]. MEDiscuss.org; 2026 [cited ]. Available from:
