Albumin: What Your Lab Value Means

What is albumin?

Albumin is a protein. It makes up around 60 percent of the total protein in blood serum. It is mainly produced in the liver cells (hepatocytes). Albumin serves, among other things, to buffer the pH value and as a readily available source of energy. However, it also has other important functions:

Albumin and the colloid osmotic pressure

The blood proteins maintain the so-called colloid osmotic pressure. It is around 25 mmHg (equivalent to around 3.3 kPa) in the plasma and is important for maintaining the balance between the dissolved particles (colloids) inside and outside the cells. If the colloid osmotic pressure falls, increased outflow of plasma water from the cells leads to the formation of edema. As albumin makes up the largest proportion of blood proteins, it is also the most important factor in maintaining colloid osmotic pressure.

Albumin as a transport protein

Albumin is an important transport substance in the bloodstream. This applies both to the body’s own substances and to substances that are supplied to the body from outside. Among other things, albumin binds and transports

  • Hormones such as cortisol and thyroxine
  • vitamin D
  • fatty acids
  • Bilirubin (a breakdown product of the red blood pigment)
  • enzymes
  • Amino acids (building blocks of enzymes)
  • Electrolytes (magnesium, calcium)
  • Metals (copper ions)

When is albumin determined?

The albumin value is determined, among other things, for

  • Chronic liver diseases (liver cirrhosis, fatty liver, etc.)
  • Protein loss via the kidneys or the gastrointestinal tract
  • Clarification of water accumulation in the tissue (edema)
  • Protein malnutrition

The doctor can determine albumin in blood serum as well as in urine and cerebrospinal fluid (CSF). For the determination he needs either:

  • 20 ml spontaneous morning urine or urine collected over 24 hours
  • 1 ml blood serum
  • three sterile cerebrospinal fluid samples

albumin: Standard values

The following standard values apply for albumin in serum, depending on age:

Serum albumin

up to 4 days

2800 – 4400 mg/dl

5 days to 13 years

3800 – 5400 mg/dl

14 to 17 years

3200 – 4500 mg/dl

from 18 years

3500 – 5200 mg/dl

The albumin in the morning urine is normally less than 20 mg/l (applies from the age of 3 years). The measured value for albumin in the 24-hour urine collection is normally less than 30 mg/d (milligrams per day).

If the albumin values in the urine (morning or collected urine) are above the limit values, the doctor distinguishes between micro- and macro-albuminuria depending on the extent of the increase:

  • Microalbuminuria (moderate albumin loss): 20 to 200 mg/l in the morning urine or 30 to 300 mg/day in the collected urine
  • Macroalbuminuria (severe albumin loss): >200 mg/l in morning urine or >300 mg/day in collected urine

age

Albumin quotient CSF/serum (x0.001)

Newborns

< 28

Infants in the 1st month

< 15

Infants in the 2nd month

< 10

Infants in the 3rd month

< 5

Children between 4 months and 6 years

< 3,5

Children between 6 and 15 years

< 5

over 15 and up to 40 years

< 6,5

over 40 years

< 8

When is albumin low?

If the blood albumin is too low, this is referred to as hypoalbuminemia or hypoalbuminemia. It occurs with:

  • cirrhosis of the liver, acute hepatitis, toxic liver damage
  • Amyloidosis (diseases with deposition of altered proteins in the body)
  • Protein loss via the kidneys (nephrotic syndrome) or the gastrointestinal tract (exudative enteropathy with watery diarrhea)
  • Malnutrition or undernourishment (for example kwashiorkor)
  • Burns or exudative skin diseases such as dermatitis
  • Excess fluid (hyperhydration, for example due to infusion therapy or during pregnancy)
  • advanced cancer
  • hereditary albumin deficiency (anemia or hypalbuminemia)

Low albumin in the urine or cerebrospinal fluid is of no significance.

When is albumin elevated?

If there is a lack of fluids (dehydration) – for example due to vomiting, increased urination or diarrhea – the blood albumin is too high. However, this is only a relative increase in albumin.

An increased concentration of albumin in the cerebrospinal fluid or an increased albumin quotient of cerebrospinal fluid/serum can indicate meningitis, Guillain-Barré syndrome, cerebral infarction, brain or spinal cord tumors or craniocerebral trauma, for example.

What to do in case of altered albumin?

Hypoalbuminemia (hypoalbuminemia) is treated according to the underlying disease. If the cause is a loss of protein via the kidneys, for example, the doctor may administer dehydrating medication or medication for high blood pressure (sartans, ACE inhibitors, etc.). If there is a pronounced albumin deficiency, the doctor may administer an albumin replacement solution containing five to 20 percent albumin.

What to do in case of albuminuria?

If the excretion of albumin in the urine is increased, the doctor must check whether the loss of albumin occurs regularly. To do this, he or she will carry out three or more albumin tests over the next six to eight weeks. If microalbuminuria is present, a check-up is necessary two to three times a year. If there is a more pronounced loss of albumin (macroalbuminuria), the doctor must clarify the cause of the kidney damage.

What to do if there is increased albumin in the cerebrospinal fluid?