Albumin in Urine

Albumin is a major blood protein that is produced in the liver. Albumin is the most abundant blood plasma protein, accounting for 55% of the total protein in plasma. Understanding albumin in urine causes and symptoms involves recognizing that albuminuria, or the presence of albumin in urine, can indicate kidney damage or dysfunction, often linked to conditions like diabetes, hypertension, or kidney disease.

What is Albumin?

Albumin is the most prominent circulating protein in plasma. It is a globular protein which constitutes half of the total protein content (3.5 to 5 g/dL) of plasma in humans. Albumin is produced by liver hepatocytes and promptly discharged into the circulation at a rate of 10 to 15 grams per day. The liver stores very little albumin, and the vast majority of it is quickly discharged into the circulation.

Serum albumin has an important role in regulating plasma oncotic pressure in humans as well as transporting endogenous and exogenous (i.e., drug) ligands. Albumin binds and transports various substances in the blood, including hormones, fatty acids, bilirubin, drugs, and metabolites. It acts as a carrier protein.

Structure of Albumin

Albumin has a globular structure, with a single polypeptide chain folded that consists of three homologous domains that combine to produce a heart-shaped protein. Each domain is composed of two subdomains that share structural features. The primary ligand binding sites on human serum albumin are situated in hydrophobic cavities in subdomains IIA and IIIA, which have comparable chemistry.

Albumins are structurally identical, with each domain comprising five or six disulfide links. It contains multiple binding sites for various molecules, including fatty acids, bilirubin, and drugs. These binding sites are crucial for its transport function. Albumin contains 35 cysteine residues, which are involved in the formation of disulfide bonds, contributing to its stability.

Albumin in Urine – Albuminuria

Albumin in the urine, known as albuminuria (sometimes referred to as proteinuria), is an indicator of kidney dysfunction or damage. Albumin is a protein that is normally found in the blood, and healthy kidneys filter out waste products from the blood while preventing the loss of albumin in the urine.

Albuminuria is an early sign of kidney disease, and it can be detected before other symptoms appear. Detection of albumin in the urine is done through a simple urine test called a urine albumin-to-creatinine ratio (UACR) or a urine dipstick test.

Albuminuria

Albumin in Urine Symptoms

Most patients with albuminuria (proteinuria) may have no symptoms. If symptoms are present, you may observe any of the following:

• Foamy urine
• Puffiness around the eyes, particularly in the morning.
• Frequent urination (peeing more than normal).
• Swelling of the feet, ankles, abdomen, or face.

Symptoms of

Albumin in Urine Causes

Some of the most prevalent causes of transitory (short-term) albuminuria are:

• Dehydration (not consuming enough water).
• High-intensity workout.
• Fever or infection.
• Heart failure exacerbation (flare-up).

Treatment for Albuminuria

Treatment for albuminuria typically involves managing the underlying cause, such as controlling blood sugar levels in diabetes or managing blood pressure. Lifestyle changes, such as adopting a healthy diet, exercising regularly, and avoiding smoking, can also help protect kidney function.

Albumin in Urine Normal Range

The normal range for albumin in urine is less than 30 milligrams per gram (mg/g) of creatinine. This is often expressed as less than 30 milligrams per gram of creatinine (mg/g Cr) in a spot urine sample.

Microalbuminuria is a condition where there is a slightly elevated level of albumin in the urine, typically ranging between 30 to 300 milligrams per gram (mg/g) of creatinine. Microalbuminuria can be a warning sign of underlying kidney disease, especially diabetic nephropathy (kidney disease caused by diabetes) or hypertensive nephropathy (kidney disease caused by high blood pressure).

Clinical albuminuria is a condition where there are elevated levels of albumin in the urine that can be detected through standard clinical tests. Clinical albuminuria often indicates more advanced kidney damage or disease.

Albumin in Urine	Normal Range	Microalbuminuria	Clinical Albuminuria
Level	<30 mg/g creatinine	30-300 mg/g creatinine	>300 mg/g creatinine
Interpretation	Healthy kidneys	Early sign of kidney damage	Significant kidney damage
Clinical Implications	No significant kidney disease detected	Early detection of kidney disease, increased risk of kidney disease progression	Kidney disease, increased risk of kidney failure and cardiovascular disease

Albumin in Urine Test

The albumin levels in urine are checked with a simple urine sample. No special collection or preparation is necessary before this test, and only about 2 tablespoons of urine are needed.

Laboratrory method: The primary method for diagnosing albuminuria is through a urine test known as the urine albumin-creatinine ratio (uACR). Your uACR results provide insight into the extent of albuminuria, if present. Lower values are preferable in this test, ideally below 30. A result of 30 or above indicates a heightened risk of complications. The greater the value, the greater the risk.

Dipstick test: A dipstick test employs a plastic testing strip coated with a reactive substance. When immersed in a urine sample, it promptly reveals the presence of albumin.

Other Tests: If your uACR significantly exceeds the desired range, additional tests may be advised to gain further insight into the underlying causes of your albuminuria.

• Kidney biopsy: particularly if there are suspicions of glomerular disease. This procedure aids in identifying the root cause of kidney disease and assessing the extent of kidney damage.
• Imaging studies: particularly if concerns about kidney cancer, kidney stones, or structural abnormalities within the kidney arise. Modalities such as ultrasound or CT scans are employed to visualize your kidneys and urinary tract, providing detailed images for evaluation.

How to Reduce Albumin in Urine

Reducing albumin in the urine involves addressing the underlying conditions or factors contributing to its elevation. Some of the ways of reducing urine in albumin in urine are:

• Adopt a nourishing, well-rounded diet.
• Keep your weight within a moderate range.
• Monitor your salt and sodium consumption.
• Engage in regular physical activity and exercise.
• Be mindful of the quantity and quality of protein in your diet.
• Discuss with your doctor any other medications you routinely take.

Functions of Albumin

Albumin is a major plasma protein which performs several crucial functions in the body:

Oncotic Pressure Regulation

• Albumin plays a crucial role in maintaining the oncotic pressure in the blood vessels.
• This pressure gradient helps to keep water within the blood vessels, preventing excessive fluid leakage into the tissues.

Transport function

• It acts as a carrier protein, transporting various substances in the bloodstream.
• For example, it binds to fatty acids, facilitating their transport, and it also binds to bilirubin, aiding in its transport to the liver for excretion.

pH Regulation

Albumin helps to buffer changes in blood pH by binding to hydrogen ions (H⁺) and other ions, contributing to the maintenance of normal blood pH levels.

Antioxidant properties

• Albumin has the capacity to bind and transport certain metals (e.g., copper, nickel), preventing them from participating in oxidative reactions that could damage tissues.
• It also binds and inactivates some free radicals, exhibiting antioxidant properties.

Anticoagulant properties

Albumin binds to certain coagulation factors, modulating their activity and contributing to the regulation of blood coagulation.

Nutritional reserve

Albumin serves as a reserve of amino acids that can be used by the body in times of nutritional deficiency or increased metabolic demand.

Conclusion – Albumin in Urine

Albumin in urine serves as a vital marker for kidney health, with elevated levels often indicating underlying kidney damage or dysfunction. Understanding the significance of albuminuria involves recognizing its association with conditions such as diabetes, hypertension, or kidney disease. Diagnosis typically relies on urine tests such as the urine albumin-creatinine ratio (uACR), while further assessments like kidney biopsy or imaging studies may be necessary for a comprehensive evaluation. Regular monitoring and collaboration with healthcare professionals are essential for optimal management and prevention of complications related to elevated albumin levels in urine.

FAQs on Albumin in Urine

What is Albumin?

Albumin is a major blood protein synthesized primarily in the liver. It plays a crucial role in maintaining blood pressure and volume by regulating oncotic pressure, which helps to keep water within blood vessels.

How is Albumin Produced?

Albumin is primarily synthesized in the liver by hepatocytes at a rate of 10 to 15 grams per day.

What Level of Albumin Indicates Kidney Failure?

A level of albumin exceeding >300 mg/g creatinine in urine indicates significant kidney damage, which can progress to kidney failure.

What are the Symptoms of hIgh Albumin Levels?

Symptoms of high albumin levels may include swelling (edema), particularly in the ankles, legs, and abdomen, as well as foamy urine and changes in urine output.

What is the Normal Range of Albumin in Urine?

The normal range of albumin in urine is typically <30 mg/g creatinine.

What are the Main Functions of Albumin in the Bloodstream?

Albumin serves several functions, including maintaining oncotic pressure, transporting substances such as fatty acids and bilirubin, regulating blood pH, acting as an antioxidant, and modulating blood coagulation.

What are the Common Causes of Albuminuria?

Common causes of albuminuria include diabetes, hypertension, glomerulonephritis, chronic kidney disease, heart failure, and preeclampsia.

How is Albuminuria Diagnosed, and What Tests are Used for Detection?

Albuminuria is diagnosed through a simple urine test called a urine albumin-to-creatinine ratio (UACR) or a urine dipstick test.