Ethier JH, Kamel KS, Magner PO, Lemann J, Halperin ML. The transtubular potassium concentration in patients with hypokalemia and hyperkalemia. Am J Kidney Dis. 1990;15(4):309-15.

Choi MJ, Ziyadeh FN. The utility of the transtubular potassium gradient in the evaluation of hyperkalemia. J Am Soc Nephrol. 2008;19(3):424-6.

Dr. Mitchell L. Halperin

//outputs
var calc_output = [];

//user inputs
var uk = parseFloat(uk);
var pk = parseFloat(pk);
var uosm = parseFloat(uosm);
var posm = parseFloat(posm);

//calculation
var u = (uk / pk) / (uosm / posm);

u = u.toFixed(0);
var msg = 'Transtubular Potassium Gradient (TTKG)';

if (u >=8 && u <= 9) {
 msg += ' TTKG values between 8 and 9 are considered normal in patients with a normal diet';
}
 
if (pk < 3.5) {
 if (u >= 3) {
 msg += ' TTKG ≥3 in hypokalemia suggests renal potassium wasting';
 }
 else if (u < 3) {
 msg += ' TTKG <3 is expected in hypokalemia';
 }
}

if (pk > 5) {
 if (u > 10) {
 msg += ' TTKG >10 in hyperkalemia suggests normal renal excretion of potassium';
 }
 else if (u >= 7) {
 msg += ' TTKG ≥7 expected in hyperkalemia';
 }
 else if (u < 7) {
 msg += ' TTKG <7 in hyperkalemia suggests hypoaldosteronism';
 }
}

//result user sees
calc_output.push({
name: 'mini',
value: u,
value_text: '',
message: 'TTKG'
});

calc_output.push({
name: 'Output',
value: u,
value_text: '',
message: msg
});

Transtubular Potassium Gradient (TTKG)

uosm

posm

May help in assessment of hyperkalemia or hypokalemia.

TTKG

The Transtubular Potassium Gradient (TTKG) determines etiology of hyperkalemia or hypokalemia.

Urine Potassium

Urine Osmolarity

Osmoles (Osm)

Potassium

FEUrea

FENa

RIFLE Criteria

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Calc Function