Significant diurnal variations, high in the morning (6-8 AM). Releases in bursts, levels vary by minute.
Pregnancy, menstruation, stress, rheumatoid factor
Patients taking glucocorticoids
0-4 mo: 2.0-4.5 g/dL
4 mo-16 y: 3.2-5.2 g/dL
>16 y: 3.5-4.8 g/dL
Two dye-binding methods, bromocresol green (BCG) and bromocresol purple (BCP), are in routine use.
BCG overestimates albumin in serum due to poorer specificity for the analyte.
BCP underestimates in pediatric patients on hemodialysis and chronic renal failure.
0-1 y: 150-350 IU/L
1-16 y: 30-300 IU/L
>16 y: 30-115 IU/L
Day-to-day variations (5-10%)
Higher in African American men (15%) and women (10%) compared to other racial/ethnic groups
Recent food ingestion, smoking, increased BMI (25%), drugs: penicillin, antiepileptic drugs, antihistamines, cardiovascular drugs
Use of oral contraceptives
AFP, tumor marker
Not recommended as a screening procedure to detect cancer in the general population
Tumors of the GI tract, liver damage (e.g., cirrhosis, hepatitis, or drug or alcohol abuse), and pregnancy
Smoking tobacco (10%)
Inflammatory bowel disease
Some dietary supplements, herbal remedies, and vitamins can cause liver toxicity, leading to a rise in AFP levels.
Not useful to assess the degree of dysfunction (e.g., in Reye syndrome, hepatic function improves and the ammonia level falls, even in patients who finally die of these disorders)
Levels are not always high in all patients with urea cycle disorders.
The presence of ammonium ions in anticoagulants
High-protein diet, GI hemorrhage, increases due to cellular metabolism: 20% in 1 h and 100% by 2 h, prolonged tourniquet application
Not recommended as a general screening test
Depending on the titer, normal healthy population can have 5-20% positive test results.
Drugs (carbamazepine, chlorpromazine, ethosuximide, hydralazine, isoniazid, mephenytoin, methyldopa, penicillins, phenytoin, primidone, procainamide, and quinidine)
Viral illness and infections
Bilirubin total and direct
0-1 d: 0.0-6.0 mg/dL
1-2 d: 0.0-8.0 mg/dL
2-5 d: 0.0-12.0 mg/dL
5 d-4 mo: 0.3-1.2 mg/dL
>4 mo: 0.3-1.2 mg/dL
Day-to-day variation (15-30%)
Lower in African Americans
Fasting up to 48 h
Exposure to light
Acetyl salicylic acid
Need to interpret with total protein and albumin levels
0.8 mg of calcium is bound to 1.0-g albumin in serum. To correct, add 0.8 mg/dL for every 1.0 g/dL that serum albumin falls below 4.0 g/dL.
Venous stasis during blood collection by prolonged application of tourniquet
Hyponatremia (<120 mmol/L)
Hyperphosphatemia (e.g., laxatives, phosphate enemas, chemotherapy of leukemia or lymphoma, rhabdomyolysis)
0-2 y: 20-25 mmol/L
2-16 y: 22-28 mmol/L
>16 y: 24-32 mmol/L
80-90% present as bicarbonate and is general guide to body’s buffering capacity
Mercurial and thiazide diuretics
Ammonium chloride, aspirin, chlorothiazide diuretics, methicillin
Not recommended for screening asymptomatic women
Not increased in mucinous adenocarcinoma
Different manufacturer assays do not produce similar value. Should not be used interchangeably.
Pleural effusion or inflammation
Peritoneal effusion or inflammation, cirrhosis, severe liver necrosis (66%), disorders of the GI tract, liver, and pancreas
Renal failure, healthy persons (1%)
African American and Asian women
Intraindividual variation (10%)
Seasonal variation (8%) higher in the winter than in summer
Positional variation is 5% and 10-15% lower when phlebotomized sitting or recumbent, respectively, as opposed to standing.
Pregnancy, drugs: beta blockers, anabolic steroids, vitamin D, oral contraceptives, and epinephrine
Smoking, alcohol, renal failure
Hypothyroidism, glycogen storage disease, biliary cirrhosis, hepatocellular disease
Prostate and pancreatic neoplasms
Acute illness such as a heart attack
Not a screening test for wellness and should only be used in the diagnosis and monitoring of a patient who appears to have an inflammatory process
Elevated levels are nonspecific and should not be interpreted without a complete clinical history.
Influenced by genetics, age, and sedentary lifestyle, stress, exposure to environmental toxins, and diet that specifically contains refined, processed, and manufactured foods
Patients treated with carboxypenicillins
0-15 mm/h in men 0-20 mm/h in women
Not a good screening test
Compared to the ESR, CRP is a more sensitive and specific marker of the acute phase reaction and is more responsive to changes in the patient’s condition.
There are only two circumstances where the erythrocyte sedimentation rate is superior—detecting low-grade bone and joint infections and monitoring disease activity in systemic lupus erythematosus.
Increased fibrinogen; increased gamma- and beta globulins
Drugs (dextran, penicillamine, theophylline, vitamin A, methyldopa, methysergide)
Technical factors (e.g., hemolyzed sample, high temperature in the laboratory)
Abnormally shaped RBCs (sickle cells, spherocytes, acanthocytes)
Microcytosis, HbC disease, hypofibrinogenemia
Technical factors (low temperature in the laboratory, clotted blood)
Drugs (quinine, salicylates, high steroid levels, drugs that cause high glucose levels)
Male: 23-336 ng/mL (in patients with normal iron stores, it should be >30 ng/mL)
Female: 11-306 ng/mL
In hepatic, malignant, and inflammatory conditions, ferritin levels can be normal. In such cases, bone marrow stain of iron may be used to exclude iron deficiency.
Liver and kidney disease, malignancy
Obesity and age
Sensitive but nonspecific indicator of biliary disease
Half-life (7-10 d); in alcoholassociated liver injury, the half-life is increased to as much as 28 d, suggesting impaired clearance.
Day-to-day variations (10-15%); approximately double in African Americans
Higher BMI (25-50%)
Approximately one third of all conceptions end in natural termination. This may produce positive results when testing early in the pregnancy followed by negative results after the natural termination.
Human antimouse antibody (HAMA) or heterophilic antibody
Elevated LH levels due to low testosterone can lead to false positives.
Cirrhosis of the liver
Inflammatory bowel disease
Smoking tobacco (20%)
False negatives in urine tests can be caused by drinking large amounts of fluids and taking diuretics, anticonsultants, anti-Parkinson drugs, tranquilizers, hypnotics, or certain antihistamines before the test.
More specific for pancreatitis than is for serum amylase; diagnosis of peritonitis, strangulated or infarcted bowel, pancreatic cyst
Cholinergic drugs, opiates
Inherent biologic variability due to hormone pulsatility and diurnal variation, choice of tube for sample collection, as well as sample stability at storage temperature
Because of a pronounced nocturnal rise in intact PTH levels observed in a small experimental male population, sampling after 10 AM for optimum discrimination between normal and those with mild primary hyperparathyroidism has been suggested.
Sedative-hypnotic drug propofol (Diprivan)
Ambulatory values are higher than sedentary values, which may decrease ≤50% (mean = 18%).
Methodologic variations exist depending upon calibrators (WHO vs. Hybritech) used by various manufacturers (22% average bias).
Prostatic massage, ≤2 times
Cystoscopy: 4 times
Needle biopsy: >50 times for ≤1 mo
Transurethral resection: >50 times, digital rectal examination, indwelling catheter
Vigorous bicycle exercise: ≤2-3 times several days, ejaculation within 24-48 h
Urinary tract infection
Antiandrogen drugs (e.g., finasteride)
PSA falls 17% in 3 d after lying in hospital
0.5-6.3 µIU/mL, depending on age and sex
Not be useful for hospitalized ill patients. Has a diurnal rhythm (50%), with peaks at 2:00-4:00 AM and troughs at 5:00-6:00 PM with ultradian variations
Human antimouse antibodies
Thyroid hormone autoantibodies
Biotin may cause falsely low values in immunometric assays.