- Grey or green top tube
- 5 mL of arterial or venous blood
Additional information
- Fasting 8-10 hrs before test (When possible)
- Client needs to rest for at least 1 hr and should not have exercised for several hours before test
- Avoid using tourniquet and instruct client not to clench fist
- Send specimen to the lab immediately, tightly capped, and in an ice slurry
- Lactic acid test is a qualitative analysis of lactic acid in the blood
- Lactic acid is present as lactate ion, which is an intermediate product of carbohydrate metabolism produced from pyruvic acid via anaerobic glycolysis on a cellular level
- Anaerobic metabolism occurs when there is insufficient energy or oxygenation occurring on a cellular level (shock, sepsis, trauma, hemorrhage, etc)
- Lactate is mostly produced in muscle cells, erythrocytes, brain cells and the gut
- Lactate is principally metabolized in the liver, and to a lower degree in the kidneys and heart
- Lactate levels depend on the rate of energy production and metabolism
- Lactate may accumulate in the body due to:
- Increased production of lactate from pyruvate as a result of hypoxia or circulatory collapse
- Decreased removal of lactate due to hepatic dysfunction
Lactate for Trauma/Sepsis:
- Lactate levels are commonly used in the evaluation of patients with trauma or sepsis
- In such cases, failure to normalize initially elevated lactate levels is a strong predictor of adverse outcome (death)
- Initial values of lactate in trauma and sepsis patients can be useful; with normal levels being reassuring; but elevated levels being most significant when they fail to rapidly normalize with therapy
Other uses for Lactate:
- Evaluation of cause and severity in patients presenting with symptoms of hypoxia and lactic acidosis
- Evaluation of tissue hypoperfusion in conditions such as:
- Shock
- Heart attack
- Severe congestive cardiac failure
- Renal failure
- Uncontrolled diabetes
- Aids in the diagnosis of metabolic acidosis of unknown etiology
- Aids to monitor hypoxia and response to treatment in critically ill patients, as in checking the adequacy of resuscitation after shock
- Along with cerebrospinal fluid (CSF) lactate test to distinguish between viral and bacterial meningitis
Additional information:
- Hyperlactatemia is seen as a mild-to-moderate (2-5 mmol/L) persistent increase in blood lactate concentration without metabolic acidosis, and no distinct clinical features. However, lactic acidosis is seen as persistently increased blood lactate levels (usually >5 mmol/L) along with metabolic acidosis
- Lactic acidosis may be clinically seen as:
- Rapid breathing
- Excessive sweating
- Cold and clammy skin
- Sweet-smelling breath
- Abdominal pain
- Nausea or vomiting
- Oliguria or anuria
- Tachypnea
- Alteration in sensorium
- Hypotension
- Kussmaul's ventilation (deep sighing respiration)
- Coma
- The etiology of lactic acidosis is classified as:
- Type A: Due to poor tissue oxygenation or tissue hypoperfusion
- Type B (Non-hypoxic conditions)
- Type B1: Caused by systemic disease
- Type B2: Caused by drugs and toxins
- Type B3: Congenital metabolic defects
- Normal day to day variation of lactate levels is about 25%
- Lactic acid levels normally rise during strenuous exercise, when blood flow and oxygen cannot keep pace with the increased needs of exercising muscles
- Elevated lactate levels of >2.5 mmol/L is associated with increased mortality rate and poor prognosis in acute conditions. Lactate levels >4-5 mmol/L has a mortality rate reaching 100%
- Lactic acidosis can be differentiated from ketoacidosis by the absence of ketosis and hyperglycemia
- Lactic acidosis may be suspected in conditions such as
- Elevated anion gap (>18 mEq/L) in the absence of other causes such as renal failure; ketosis; ethanol, methanol, or salicylate poisoning
- Increased arterial lactate-pyruvate ratio (60:1)
- Related laboratory tests include:
- Amylase
- Anion gap
- Arterial/ alveolar oxygen ratio
- Arterial blood gases
- Complete blood count
- Cultures (Blood, CSF, Sputum, Stool, Urine, Wound)
- Electrolytes
- Glucose
- Ketones
- Lactate pyruvate ratio
- Pyruvate
Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.
| Conv. Units (mg/dL) | SI Units (mmol/L) | |
|---|---|---|
| Venous blood | 5-19.5 | 0.6-2.2 |
| Arterial blood | 5-15 | 0.6-1.7 |
| Critical values |  45 | 5 |
The etiology of elevated lactate levels are classified as:
- Type A: Due to poor tissue oxygenation or tissue hypoperfusion
- Type B (Non-hypoxic conditions)
- Type B1: Caused by systemic disease
- Type B2: Caused by drugs and toxins
- Type B3: Congenital metabolic defects
Conditions associated with elevated lactic acid levels include:
- Type A
- Cardiac arrest
- Carbon monoxide poisoning
- Hemorrhage
- Hypoperfusion
- Myocardial infarction
- Pulmonary embolism
- Seizures
- Sepsis with shock
- Severe anemia
- Severe hypoxemia
- Shock such as cardiogenic, septic, and hypovolemic
- Status asthmaticus
- Trauma with shock
- Type B1
- Diabetes mellitus
- Malignancies such as leukemia and lymphoma
- Pheochromocytoma
- Renal failure
- Reye's syndrome
- Sepsis
- Severe hepatic disease
- Severe respiratory alkalosis
- Short-bowel syndrome
- Thiamine deficiency
- Type B2
- Acetaminophen
- Albuterol
- Anticonvulsants (long-term use)
- Carbamazepine
- Carbon Monoxide
- Catecholamines
- Cyanide
- Epinephrine (IV infusion)
- Ethanol
- Ethylene Glycol
- Fructose (IV infusion)
- Glucagon (IV infusion)
- Isoniazid
- Lactose
- Metformin
- Methanol
- Nitroprusside
- Oral contraceptives
- Phenformin
- Phenobarbital
- Propofol
- Propylene Glycol
- Ritodrine
- Salicylates
- Sorbitol (IV infusion)
- Valproic acid
- Zidovudine
- Type B3
- Glycogen storage diseases
- Type I (von Gierke's)
- Type III
- Deficiency of enzymes
- Aldolase B (Hereditary fructose intolerance)
- Fructose 1,6-diphosphatase
- Fumerase
- Glucose 6-phosphatase
- Oxoglutarate dehydrogenase
- Pyruvate carboxylase
- Pyruvate dehydrogenase
- Succinate dehydrogenase
- Defective oxidative phosphorylation
- Kearns-Sayre syndrome
- MELAS syndrome (Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke)
- MERRF (Myoclonus epilepsy associated with ragged red fibers)
- Respiratory chain defects
- Physiological
- Strenuous muscle exercise
- Hyperventilation
- Fasting
False positive levels of lactate can be due to:
- Engaging in strenuous physical activity before specimen collection
- Using a tourniquet or patient clenching fist during venipuncture
- Delay in transport or storage of the sample at room temperature before analysis enhances cellular metabolism
- Specimens not processed by centrifugation in a tightly stoppered collection container within 15 minutes of collection
Conditions associated with decreased levels of lactic acid include:
- Weight loss
- Drugs and toxins
- Carbicarb
- Dichloroacetate
- L-Carnitine
- Morphine
- Omega-3 fatty acids
- Sodium bicarbonate
- Thiamine
False low levels of lactate can be due to:
- Elevated levels of the enzyme lactate dehydrogenase (LDH), as this enzyme reacts with the available lactate substrate
- Hemoglobin and bilirubin may decrease results in some assays
- Borruto F et al. Screening of foetal distress by assessment of umbilical cord lactate. Clin Exp Obstet Gynecol. 2006;33(4):219-22.
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- Nordstrom L et al. Fetal and maternal lactate increase during active second stage of labour. BJOG. 2001 Mar;108(3):263-8.
- Salpeter S et al. Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus. Cochrane Database Syst Rev. 2006 Jan 25;(1):CD002967.
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- Yousef E et al. Lactic acidosis and status asthmaticus: how common in pediatrics? Ann Allergy Asthma Immunol. 2002 Dec;89(6):585-8.