Albumin is a protein produced by the liver and found in blood plasma. An albumin blood test is used to assess overall health and evaluate liver and kidney function. It helps maintain fluid balance in the bloodstream and facilitates the circulation of essential substances such as vitamins, enzymes, and hormones.
What is the aim of albumin estimation?
| Purpose of Albumin Test | Reason |
|---|---|
| Assess liver function | The liver produces albumin, and low levels may indicate liver damage or disease. |
| Monitor kidney function | Damaged kidneys can leak albumin into the urine, leading to low blood albumin levels. |
| Evaluate nutritional status | Malnutrition or protein deficiency can cause low albumin levels. |
| Detect dehydration | Dehydration can lead to elevated albumin levels due to concentrated blood. |
| Assist in diagnosing other conditions. | Certain inflammatory conditions, infections, or autoimmune diseases can affect albumin levels. |
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Evaluate nutritional status
Measurement of plasma albumin levels is recommended for assessing malnutrition, as they directly change based on the diet. However, because albumin has a relatively long half-life of 15-19 days, changes in protein intake may not be immediately reflected in albumin levels. The most common cause of low albumin levels is acute and chronic inflammation. Albumin levels do not correlate well with the severity of malnutrition unless inflammation or other factors causing decreased blood albumin are ruled out.
Hyperglycemia treatment monitoring
Glycated hemoglobin is commonly used to monitor long-term diabetes treatment. Studies have shown that measuring fructosamine (glycated albumin) effectively monitors diabetes in the mid-term.
Monitor kidney function regularly.
The renal glomeruli function as filters for molecules. The rate at which substances pass through these glomeruli is inversely related to their molecular size. The glomerular basement membrane has a negative charge, preventing negatively charged proteins’ excretion. Structural abnormalities in the glomeruli, such as enlarged pores or loss of negative charges, result in the excretion of proteins in urine.
In a normal state, a small amount of albumin (less than 1% of blood) enters the glomerular filtrate. Most albumin molecules (95% to 99%) are reabsorbed by the proximal tubules and subsequently degraded by lysosomal enzymes within the tubular cells. The amino acids produced from this breakdown are recycled back into the bloodstream for reuse. The natural excretion of albumin is minimal.
Urinary albumin excretion increases in the early stages of kidney disease due to its low molecular weight, making it a valuable marker for evaluating these diseases.
Evaluation of changes in bound ligand levels
Compounds such as hormones, ions, and drugs are only physiologically active when they are free and unbound. The bound forms of these compounds to albumin are often inactive. Changes in plasma albumin concentration can impact the total concentration of these compounds, particularly their binding component. However, the free part is less likely to be affected.
When interpreting blood test results for these compounds, it is important to take into account the albumin concentration. For instance, a calcium level of 8 mg/dL may indicate hypocalcemia in someone with a normal albumin concentration. Still, it could be considered normal for someone with below-normal albumin levels. This issue should also be taken into account when prescribing drugs that bind to albumin.
