Reference intervals
Isopropanol
Not detected
Acetone*
Not detected
*Acetone is measured together as it is the major metabolite of isopropanol.
Conversion factor:
Isopropanol
mg/dL x 0.166 = mmol/L
mmol/L x 6.01 = mg/dL
Acetone
mg/dL x 0.172 = mmol/L
mmol/L x 5.81 = mg/dL
Uncertainty of measurement
Isopropanol = 12% at 13 mmol/L
Acetone = 13% at 13 mmol/L
GC - headspace
Note: The enzymatic test routinely used for ethanol measurement does not measure isopropanol or other related substances (methanol, ethylene glycol, acetone, acetaldehyde). These must be specifically requested, as they are measured by another method.
Isopropanol
Common sources - rubbing alcohol, hand sanitizers
Clinical features of isopropanol intoxication usually manifest within 30 to 60 min after ingestion but can take up to 2 to 4 h to develop. The clinical findings include abdominal pain, nausea, vomiting diarrhoea, depressed sensorium and hypotension in severe toxicity. Unlike methanol or ethylene glycol poisoning, it does not cause metabolic acidosis unless hypotension is sufficient to induce lactic acidosis. Topical use of hand sanitizers does not cause measurable elevation of blood isopropanol (or ethanol).
Although serum concentrations of isopropanol do not necessarily correlate with clinical status, it is thought that toxic effects generally occur with concentrations above 8.3 mmol/L. Blood isopropanol concentrations greater than 25 mmol/L may be associated with deep coma, greater than 33 mmol/L may lead to death.
There are no antidotes for isopropanol poisoning. Supportive treatments are often sufficient but haemodialysis may be needed if the serum concentration is greater than 8.3 mmol/L or if hypotension or lactic acidosis is present. Since the primary metabolite (acetone) is less toxic than isopropanol, unlike methanol poisoning there is no indication for ethanol following isolated isopropanol ingestion.
Isopropanol may be detected at low concentrations in the serum of patients with severe diabetic or alcoholic ketoacidosis, due to endogenous reduction of acetone to isopropyl alcohol.
Acetone
Acetone can be detected after 30 minutes in the serum and within 3h in the urine after ingestion of isopropanol. Even if isopropanol is not detected in serum, acetone concentration above what would normally be expected from endogenous production could indicate recent isopropanol exposure.
Acetone can also be raised in diabetic or alcoholic ketoacidosis. As circulating acetone can be reduced to isopropanol, in the setting of ketoacidosis, acetone levels are usually higher than isopropanol levels (in millimolar terms). Unlike patients with isopropanol poisoning, these patients will usually present with metabolic acidosis and increased blood glucose level if diabetic.
Acetone interferes with Jaffe creatinine assay
Markedly high acetone can interfere with Jaffe creatinine assay and give falsely high creatinine results; Rutherford et al showed 50mmol/L of acetone caused approx. 20 umol/L increase of plasma creatinine if measured by Jaffe assay. If any concerns, please contact the on-call Chemical Pathologist via Lablink to discuss.
References
1. Slaughter RJ, Mason RW, Beasley DM, Vale JA, Schep LJ. Isopropanol poisoning. Clin Toxicol (Phila). 2014;52(5):470-8.
2. Kraut JA, Kurtz I. Toxic alcohol ingestions: clinical features, diagnosis, and management. Clin J Am Soc Nephrol. 2008;3(1):208-25.
3. Isopropanol [Available from: https://www.toxinz.com/Spec/2258564 .
4. Wilson ME, Guru PK, Park JG. Recurrent lactic acidosis secondary to hand sanitizer ingestion. Indian J Nephrol. 2015;25(1):57-9.
5. Rutherford NJ, Huges CE, Okinkemelu D, Sephel GC, Nichols JH, Shajani-Yi Z. Suspected Renal Impairment Following Isopropanol Ingestion. JALM. 2019;(04:01)
Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.
If the query concerns a specific patient please include the NHI number in your email.
If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).
Individual chemical pathologists may be contacted but will not be available at all times.
After-hours : contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.
Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402
Dr Cam Kyle: CampbellK@adhb.govt.nz ext 22052
Dr Weldon Chiu: WeldonC@adhb.govt.nz ext. 23427
Dr Campbell Heron: CHeron@adhb.govt.nz ext. 23427
Dr Sakunthala Jayasinghe: Sakunthala@adhb.govt.nz ext. 23427
Please send refrigerated (2-8 degrees).