Renal function

Trans-tubular K gradient (TTKG)

Distal nephron K handling. Valid only when urine osm > serum osm and U[Na] > 25 mEq/L.

hyperkalemia

Required inputs

  • Urine K (mEq/L)
  • Plasma K (mEq/L)
  • Urine osm (mOsm/kg)
  • Plasma osm (mOsm/kg)

Equation or source

Halperin ML. Nephron 1986;44:184. Note: superseded by urine K:Cr in current practice — interpret with caution.

Provenance and release status

Equation / algorithm
Distal nephron K handling. Valid only when urine osm > serum osm and U[Na] > 25 mEq/L.
Formula version
ttkg-v1
Tool version
2.4.0
Clinical risk class
B. CLINICAL DECISION-SUPPORT CALCULATOR
Release status
Under clinical review
Source status
Direct primary source identifier not yet resolved
Clinical review status
Under clinical verification
Clinical review date
Clinical review date not yet documented

DOI / PMID / direct guideline identifier not yet documented.

Assumptions

  • Entered values and units are accurate and apply to the population described by the cited source.
  • The published equation or rule is being used without a patient-specific clinical adjustment.

Important limitations

  • The result does not replace clinical assessment or establish a diagnosis.
  • Performance outside the source population may differ.
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