Reference Ranges and Critical Results

critical urea

>/= 35.0 mmol/L

normal urea:creatinine ratio

40:1 to 100:1

urea/creatinine ratio indicating renal

<40:1

urea/creatinine ratio indicating prerenal

>100:1 with increased urea and normal creatinine

urea/creatinine ratio indicating postrenal

>100:1 with increased urea and increased creatinine

critical creatinine

>600 umol/L

critical uric acid

no critical range

chronic kidney disease eGFR result

<60 mL/sec/1.73m² for 3 months

osmolality RR (serum)

275-295 mOsm/kg

critical osmolality (serum)

<265 mOsm/kg or >320 mOsm/kg

osmol gap RR

</= 10 mOsm/kg

value indicating hyponatremia

<135 mmol/L

sodium value associated with mortality

>160 mmol/L

renal threshold for sodium

110-130 mmol/L

critical sodium

<120mmol/L or >160mmol/L

critical potassium

</= 3.0 mmol/L or >/= 6.0 mmol/L

critical chloride

</= 80mmol/L or >/= 125 mmol/L

normal sweat chloride

<40 mmol/L

abnormal sweat chloride

>60mmol/L

anion gap RR (without K+)

7-16 mmol/L

anion gap RR (with K+)

10-20 mmol/L

causes of increased anion gap

Methanol toxicity

Uremia from renal failure

Diabetic ketoacidosis

Paraldehyde

Infection, Iron, Isoniazid toxicity

Lactic acidosis

Ethylene glycol, Ethanol toxicity

Salicylate toxicity, Starvation

critical total calcium

<1.70 or >3.00 mmol/L

result suggestive of hypercalcuria

>0.57

critical ionized calcium

<0.80 mmol/L

critical inorganic phosphate

<0.33 mmol/L or >3.00 mmol/L

life threatening hypermagenesemia result

>/= 5.0 mmol/L

critical magnesium

<0.50 or >2.00 mmol/L

CSF lactate result indicating bacterial meningitis

>4.0 mmol/L