Causes of Proteinuria
While urine test strips can detect the presence of proteinuria, they can’t diagnose the exact cause. That’s because many conditions can lead to excessive protein levels in urine, from high blood pressure to kidney failure [2, 7].
Medical professionals categorize the disorders associated with proteinuria into three groups: prerenal, renal, and postrenal. Each group is characterized by different amounts and types of protein, along with varying degrees of kidney damage [1, 2].
Prerenal
Prerenal proteinuria is caused by disorders that affect the plasma before it reaches the kidneys. This type typically occurs when the body produces higher-than-normal amounts of hemoglobin, myoglobin, and other proteins. The kidneys can’t filter these compounds out of the blood quickly enough, causing them to overflow into the urine — much like water spilling out of a pot when it boils over on a stove [3].
Overflow proteinuria is usually caused by transient — or temporary — conditions. For example, an infection may trigger your body to produce excess hemoglobin. Once you clear the infection, these protein levels usually return to normal, and the proteinuria resolves [3].
While prerenal proteinuria isn’t directly caused by kidney disease, low molecular proteins like myoglobin can damage the kidney tubules. It’s critical to seek medical help for serious infections to prevent acute kidney damage [1, 2].
Renal
Renal disease often leads to proteinuria when the kidneys become too damaged to filter waste properly. Renal proteinuria can be caused by two types of kidney damage: glomerular and tubular [2].
The kidneys have a glomerular membrane that helps filter plasma from the bloodstream. If this membrane becomes damaged, it may no longer filter serum proteins effectively, enabling them to enter the urine [3].
Many factors can cause glomerular proteinuria, including [3]:
- Excessive exercise
- Dehydration
- Hypertension
- Exposure to toxic substances
- Autoimmune diseases, such as lupus erythematosus
- Streptococcal glomerulonephritis
- Preeclampsia during pregnancy
The kidneys also have proximal renal tubules, which help reabsorb albumin and other essential proteins. If these tubules get damaged, they can leak proteins into the urine instead of cycling them back into the bloodstream [1, 2].
Several factors can lead to tubular proteinuria, such as:
- Acute interstitial nephritis [2]
- Analgesics (painkillers) [2]
- Exposure to heavy metals or toxins [3]
- Immunosuppressants [2]
- Sjögren syndrome [2]
- Viral infections [3]
Medical professionals can quickly distinguish between glomerular and tubular damage by measuring the amount of protein in urine. Glomerular damage often causes significantly elevated protein levels, while tubular damage has more moderate levels.
Postrenal
After urine exits the kidney, it passes through the lower urinary tract. Postrenal proteinuria occurs if protein enters the urine during this final phase of its journey.
Here are a few conditions associated with postrenal proteinuria:
- Nephrolithiasis [3]
- Urinary tract infection (UTI) [3]
- Bladder cancer [2]
- Bacterial and fungal infections [3]
Protein in urine test strips may also give false-positive results if they get contaminated with blood from an injury or menstrual fluid [3].
Postrenal proteinuria doesn’t affect the kidneys, so it typically clears up as soon as the underlying condition resolves.
Treatment Options for Proteinuria
Proteinuria has many potential causes, so there’s no one-size-fits-all treatment plan. For example, a doctor will likely prescribe antibiotics to treat a UTI [4]. Meanwhile, acute interstitial nephritis — or swelling of the kidney tubules — may require corticosteroids or dialysis [5].
Understanding the cause and etiology is critical for treating proteinuria. Once your healthcare provider determines the source of the condition, they can recommend the most effective intervention strategies.
In other words, using urine protein test strips to detect proteinuria is just the first step. You’ll likely need additional tests to pinpoint the root cause. Otherwise, you’d be shooting arrows in the dark when it comes to treatment — potentially risking kidney damage in the process.
Test for Proteinuria With Urine Test Strips
Monitoring your urine for protein can help you catch many health conditions, from simple fungal infections to complex autoimmune disorders. By catching these disorders in the early stages, you can receive prompt treatment and increase your chances of a positive outcome.
With Diagnox’s 24-hour urine protein strips, you can test your urine anytime, anywhere. Designed for at-home and professional use, these strips deliver accurate and fast results. If the strips detect proteinuria, consult a healthcare provider to determine the underlying cause and start treatment.
