Our previous article in the “Protein in Urine” series explained, what Proteinuria is, how it may occur & the kidney conditions commonly associated with it.
This article follows-up to inform how your medical team diagnoses Proteinuria in the clinic & relevant treatment approaches that may be undertaken.
HOW DO DOCTORS KNOW THEY NEED TO ORDER TESTS FOR URINE PROTEIN LEVELS?
CLINICAL EXAMINATION
1. PATIENTS REPORT FROTHY URINE
Urine samples with Protein tend to be visibly foamy/frothy akin to the kind that you get after dissolving soap/detergents in water. The extent of foam will certainly vary with the extent of protein leakage.
Unlike bubbles in normal urine that disappear after a few seconds of flushing, the foam in urine with protein continues to persist and sometimes turns even frothier after you flush the toilet.
Frothy urine is an important symptom. However, it is also completely subject to patients’ own observations that also tend to be variable. So, doctors prefer to substantiate the patient’s observation with a simple urine routine test to assess if there is a cause for worry.
2. OEDEMA (SWELLING DUE TO FLUID) OF ANKLES & FEET
Most patients with Protein loss in urine present with swelling of ankles and feet to varying extents, that pits against pressure. In the absence of any other known cause, this swelling is because of accumulation of body fluid in these areas in response to the loss of plasma protein. The technical term for such fluid swelling is “Oedema” (pronounced as id-ee-ma).
In the case of chronic kidney disease, the extent of Oedema relates directly to the quantity of protein loss in urine.
Oedema could be a diagnosing symptom for Proteinuria as well as a late-stage complication of a known case of Sustained Protein Loss in the urine.
NOTE: Why does protein loss cause Oedema?
Plasma proteins leaking in urine could consist exclusively or majority, of Albumin. Albumin is a crucial plasma protein formed by our Liver. Among a host of life-saving functions, it helps maintain something called, the “plasma pressure”. This is different from the usual blood pressure as we know it.
A normal blood albumin level (approximately ranges between 3.5-5.5 grams/decilitre of blood) maintains a “normal plasma pressure” which in turn, keeps the fluid in our blood from crossing over to & getting accumulated in tissues. As a result, our ankles, feet, etc. are prevented from swelling-up due to fluid in normal health. Any condition causing Albumin loss in urine causes patients to get Oedema of the Ankles & feet.
3. HIGH BLOOD PRESSURE
Patients who have been losing plasma protein in urine for some time can present with High Blood Pressure, usually with an abnormal increase in the lower value of your BP recording.
Let us explain.
Every BP recording comes as a set of two numbers written as:
(a top value) / (a bottom value) (unit=mmHg)
The top value is called the “Systolic BP”. It signifies the pressure at which your heart “pumps blood out” to the body.
The bottom value is called the “Diastolic BP”. It relates to the pressure at which the heart receives used blood from the body.
As per the latest High BP guidelines by the American College of Cardiology, BP readings below 120/80 mm Hg qualify as normal. More aptly, a “Systolic Value” between 100-120 mm Hg and a “Diastolic value” between 60-80 mm Hg qualify as the normal BP range.
Patients with Sustained Protein Loss in urine and established kidney disease are unable to pump enough fluid out of the body. This increases the fluid levels in your blood, or in other words, your overall blood volume. As a result, blood from kidneys gushes back to the heart with an abnormally high “tsunami-like” force. Hence such patients typically present with an abnormal increase in the lower BP number i.e. the Diastolic BP beyond 90 mm Hg.
Please note, if Proteinuria is diagnosed at an early stage, the patient may still continue to record normal blood pressure at that point. In the absence of other health conditions, it is only when there is sustained protein loss with significant kidney damage, that the patient turns hypertensive (reports sustained high BP).
LABORATORY TESTS
Whenever your medical team suspects you may be losing plasma protein in your urine, they will order further laboratory tests. This is for confirmation and to choose an appropriate treatment plan from approved clinical protocols.
1. URINE TEST / URINALYSIS TO CONFIRM PRESENCE OF PROTEIN
A dip-strip test done as part of a Urine Routine Examination is commonly used to confirm the presence and approximate extent of Albumin (and Plasma Protein) in Urine.
The result can vary from “Nil/Negative” for a healthy Urine Sample with no protein, to “Trace“, “1+“, “2+” or “3+” (and sometimes “4+“) for the varying extents of Protein in Urine.
NOTE:
Dip-strips help to diagnose almost all cases of proteinuria except when their nature is different from the usual Plasma Proteins. Such an exception is for patients who suffer from Multiple Myeloma. They lose a specific category of “light” proteins called Bence-Jones Proteins (named after the person who found it) related to their disease process. If a patient has symptoms suggestive of Proteinuria, but test negative for urine protein with a dip strip, doctors advise special tests to look for Bence-Jones proteins. The detail on this topic will be available in future articles on Multiple Myeloma.
2. URINE TEST TO ESTIMATE QUANTITY OF PROTEIN LOSS PER DAY
To estimate the exact quantity of protein loss per day, doctors can advise patients to undergo a “Spot collection” (in one of those smaller containers). Alternatively, doctors can sometimes advise a “24-hour” urine collection in a special container (usually provided by the respective medical lab).
Lab doctors check the urine samples to analyze total protein content leaking out in urine per day. ( in milligrams (mg) or grams (g) as the case may be)
3. URINE TEST TO ASSESS “PROGNOSIS” & PLAN TREATMENT
“Prognosis” is the fancy medical term for predicting the likely course of a disease process or its outcome.
A simple, inexpensive urine test can allow a medical care team to assess the prognosis of a particular kidney condition in a patient with Proteinuria. The technical name for this test is “Protein-Creatinine Ratio (PCR)” or “Albumin-Creatinine Ratio (ACR)”.
Here, labs first carry out tests to estimate the precise quantity of protein & creatinine (a cellular waste product) in the Urine Sample. Then they divide the Urine Protein quantity with the Urine Creatinine Quantity to yield a PCR or ACR value.
| PROTEIN CREATININE RATIO (PCR) | CLINICAL NOTES |
|---|---|
| PCR < 3 | Normal, no action needed at that point |
| PCR = 3-30 | Termed "Micro-albuminuria". Could resolve itself or turn sustained. Needs annual monitoring. |
| PCR > 30 | Significant protein leakage equivalent to "1+" protein in Dip strip measurements. |
| PCR > 100 | Huge protein loss in urine per day. Associated with Oedema and High BP. Seen in advanced, irreversible chronic kidney disease and in Nephrotic Syndrome. |
FURTHER STEPS
Once the patient undergoes the clinical and laboratory workup for Proteinuria as mentioned above, further diagnosis & treatment plant is based on the PCR / ACR value.
If PCR / ACR is less than 30, the patient will simply require to undergo annual monitoring.
However, if PCR / ACR > 30, it would require the patient to do the following:
Consult a nephrologist
Nephrologists are doctors who specialize in treating diseases of the Kidney. They will assess your reports for the tests you have already undergone, and ask questions related to the following:
How and When did you notice your symptoms for Proteinuria
Whether you have developed any new symptoms after recently or not.
Your past medical history specifically relating to any viral or bacterial infections
If somebody from your immediate family or blood-relatives has had similar symptoms or is a known case of Kidney Disease.
Questions relating to your general lifestyle —
1. Diet & Daily water intake
2. Any medicines that you’ve been taking including all vitamins and nutritional supplements
3. Whether you smoke or not
4. Your average alcohol intake
5. Your exposure to narcotic drugs
Further, your nephrologist will examine your Blood Pressure, look for signs of Anaemia and check for any fluid accumulation (Oedema) within your limbs.
Based on the above, your doctor will order specific tests relating to kidney function. This will help understand the extent of progress of your Kidney Disease (if any). These tests may include:
1. BLOOD WORK
Blood tests include but are not limited to testing for your Serum Creatinine & Blood Urea levels. These fall under the purview of “Renal Function Tests”.
2. IMAGING SCANS
You will need to go to the Radiology department to get Imaging Scans of your Kidney done. These usually include getting an Ultrasonography (USG) scans to determine kidney shape/size abnormalities if any.
3. RENAL BIOPSY
In some cases, patients may be asked to get a Kidney (Renal) Biopsy at the Department of Pathology. This involves removing a minuscule piece of your kidney tissue under Local Anaesthesia. Renal Pathologists study this tissue to pinpoint the specific root cause & staging of Kidney Disease.
REFERENCES
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