3% Sulfosalicylic Acid Test for the Detection of Proteinuria

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Sulfosalicylic Acid It is used to determined presence of proteins in urine sample by turbidimetric method. Unlike the routine urine protein dipstick pad, the Sulfosalicylic Acid reaction detect globulin and Bence-Jones proteins, in addition to albumin (although it is more sensitive to albumin). In alkaline urine, the SSA reaction is a more accurate measure of urine protein content than the dipstick.

Principle of  3%Sulfosalicylic Acid Test

There are two basic approaches available for measuring proteinuria, that is turbidimetric method and colorimetric reagent strip. Sulfosalicylic acid method comes under turbidimetric method. The protein is denatured by  Sulfosalicylic Acid so that it becomes less soluble and is precipitated.

Composition of  3% Sulfosalicylic Acid solution

Sulphosalicylic acid3.0gm
Distilled water100.0ml

Appearance of 3% Sulfosalicylic Acid solution

It appears as a Colourless liquid may have slight pink tinge.

Material required for 3% Sulfosalicylic Acid Test

  • Urine sample
  • Two test tube (Test and Control)
  • Centrifuge (Optional)
  • Plastic bulb pipette
  • 3% Sulfosalicylic Acid solution

Test procedure

  • Divide the urine specimen into two portions (urine sample should be cleared if necessary by centrifugation and use the supernatant for the test) that is add about 3 ml of the urine sample in test and control tube
  • To the Test,Add 3 drops of 3%  aqueous sulfosalicylic acid direct on top of the urine sample
  • Immediately compare the test and Control by observation for turbidity

Observation and Interpretation

Observation and Interpretation
Observation and Interpretation
7.5 mg/100mlNegative
up to 20mg/100ml Trace
up to 30mg/100ml +
up to 50mg/100ml ++
up to 75mg/100ml +++

Possible Limitations

False positives

  • X-ray contrast media
  • High concentration of antibiotics, such as penicillin and cephalosporin derivatives
  • SSA test should always be performed on urine supernatant. Unless the urine sample is clear, the test must be performed on centrifuged urine. Best practice is to always used supernatant from a properly spun urine sample.
Also read  Clinical Significance of Various Crystals Found In Urine

False negatives

  • Highly buffered alkaline urine. (The urine may require acidification to a pH of 7.0 before performing the SSA test.)
  • Dilute urine
  • Turbid urine – may mask a positive reaction. Again, best practice is to always used supernatant from a properly spun urine sample.

Clinical Significance of Proteinuria

Proteinuria can occur mainly due to

  • Glomerular damage
  • Defect in tubule reabsorption 
  • chronic diseases, such as diabetes and hypertension, with increasing amounts of protein in the urine reflecting increasing kidney damage. With early kidney damage, the affected person is often asymptomatic. As damage progresses, or if protein loss is severe, the person may develop symptoms such as edema, shortness of breath, nausea, and fatigue.
  • Excess protein overproduction, as seen with multiple myeloma, lymphoma, and amyloidosis, can also lead to proteinuria.

Proteinuria is not always pathological. So there are mainly 3 types of proteinuria.
A. Accidental Proteinuria
Due to contamination of urine with vaginal seminal discharge after prostatic massage and derivation from diseased condition of genital tract or bladder accidental proteinuria is seen.
B. Functional Proteinuria
Non pathological proteinuria also called physiological albuminuria mainly seen in strenuous exercise, phyexia, exposure to cold, congestive heart failure hypertension atherosclerosis pregnancy dehydration fever if person stand in upright position for longer period. (Postural or orthostatic proteinuria)
C. Renal Proteinuria
Any condition resulting in increased permeability of urinary tract surfaces or in transduction such as glomerulonephritis diabetes nephritis associated with SLE, pyelonephritis, hereditary fructose intolerance, cystitis urinary tract, malignancies, heavy metal poisoning, eclampsia, amyloidosis, sarcoidosis, sickle cell disease, renal transplant rejection, multiple myeloma, degenerative and irritative condition and lower urinary tract.


  • Newell J.E. and Duke E., 1961, Workshop on urinalysis and renal function studies the routine examination of urine in laboratory, Chicago, American Society of Clinical Pathologist.
  • Senberg, H.D. Clinical Microbiology Procedures Handbook. 2nd Edition.
  • Jorgensen,J.H., Pfaller , M.A., Carroll, K.C., Funke, G., Landry, M.L., Richter, S.S and Warnock., D.W. (2015) Manual of Clinical Microbiology, 11th Edition. Vol. 1.
  • Lapage S., Shelton J. and Mitchell T., 1970, Methods in Microbiology’, Norris J. and Ribbons D., (Eds.), Vol. 3A, Academic Press, London.
  • MacFaddin J. F., 2000, Biochemical Tests for Identification of Medical Bacteria, 3rd Ed., Lippincott, Williams and Wilkins, Baltimore.
Also read  Urine Dipstick principle and significance of parameters

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About the Author: Arthur Westmann

DEFFE ARTHUR (AMOEBAMANN) is the founder and author of MLTGEEKS and MLTEXPO.He’s from Cameroon and is currently a Final year State Medical Laboratory Technician (MLT MA). Beyond lab works, he’s a passionate internet user with a keen interest in web design and blogging. Furthermore He likes traveling, hanging around with friends and social networking to do in his spare time.

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