Category: Tests

Creatinine testing is a diagnostic test used to assess kidney function

The creatinine test is used to assess kidney function. Normal blood creatinine is 0.6-1.4 mg/dL (or 53-115 µmol/L).

The kidneys excrete creatinine, a chemical substance that results primarily from metabolic changes in the muscles. In a healthy person, creatinine is excreted in the urine following the filtering process in the kidneys. Creatinine accumulates excessively in the plasma if the kidneys are not functioning properly.

What is creatinine?

It’s a chemical compound found in human blood and urine. Creatinine is produced as a byproduct of metabolic processes (primarily in the muscles) that break down creatine phosphate. The kidneys discharge it in the urine. Muscle mass is what determines its size. Creatinine is the fundamental tracer that allows you to monitor the function and health of the kidneys (see what tests best evaluate the work of the kidneys ).

Creatinine standards

Creatinine is found in the blood and urine and is used to test kidney function (for more information, see What Does Kidney Pain Mean?). For this indicator, your doctor may order blood and urine tests.

Blood creatinine standards

The average normal adult blood creatinine concentration is 0.6-1.4 mg/dL (or 53-115 µmol/L) .

However, creatinine values ​​can be defined in more detail by dividing patients into 3 groups.

Type of patientsstandards
men62–106 µmol/l
women44–80 µmol/l
children under 5 years of age21–36 µmol/L

Urine creatinine standards

If tested on a urine sample, normal creatinine values ​​for women are 0.74-1.57 g/day or 7-14 mmol/day and for men 1.04-2.35 g/day or 9-21 mmol/day.
These values ​​may vary from lab to lab as different methods and apparatus may be used.

When is it worth examining?

Creatinine testing is a diagnostic test used to assess kidney function. We also frequently perform them in patients being treated for diseases that cause kidney dysfunction over time, such as hypertension or diabetes, as well as in cases of abnormal urine tests.

Before surgery and diagnostic tests that use a contrast agent, the level of creatinine should also be checked. 

What does an elevated level mean?

Elevated blood creatinine levels are usually associated with worsening kidney function, but some drugs can also increase the level. However, not all abnormal results mean serious kidney damage, and it is up to the physician to interpret the results.

Creatinine level too low

Low concentration occurs in people who are malnourished, emaciated, with low muscle mass, in people with severe liver diseases.

It happens that pregnant women may have low creatinine levels. Also, taking certain medications, e.g. those with anti-inflammatory effects, may cause too low levels of this parameter in the blood.

What does the test look like?

Proper preparation for the test is essential if we want to obtain reliable, unfalsified results.

Creatinine – blood concentration test:

  • the day before you should not do intensive sports,
  • you need to go for the test on an empty stomach , i.e. do not eat anything for at least 8 hours (see what tests need to be done on an empty stomach ),
  • The test consists in puncturing a vein and drawing blood
  • the result is usually obtained after 24 hours.

In the case of urine creatinine testing, it can be performed in 2 ways: from a random, single urine sample or from a 24-hour urine collection.

Potassium in the blood – the norm, the causes of excess and deficiency

The potassium level in the blood should be between 3.5 and 5.0 mmol/l. It is uncommon to have too little or too much of this element in the blood. However, if such a condition occurs, it is necessary to seek medical attention. Potassium excess and deficiency in orgasm are both dangerous.

The role of potassium in the body

Potassium (K+) is a cation that is abundant in the body (second only to sodium). It is primarily found in the muscles, as well as the liver and red blood cells. Potassium is essential for the proper functioning of the circulatory and nervous systems.

The role of potassiumin the body:

  • affects osmotic pressure,
  • participates in ensuring the balance of the water-electrolyte and acid-base balance of the body,
  • supports the proper functioning of the heart,
  • catalyses many enzymatic reactions,
  • responsible for transmitting nerve impulses,
  • ensures proper muscle work,
  • participates in protein synthesis. 

We supply potassium to the body with food. Potassium deficiencies are very rare in healthy people who eat a balanced diet. Our diet provides enough potassium and even exceeds human needs.

Potassium in the blood 


The potassium level in the blood should be between 3.5 and 5.0 mmol/l. An ionogram is a test that measures the water and electrolyte balance of the body. It is determined by drawing venous blood from the elbow bend. Knowing how to recognize potassium deficiency or excess is important.

When should blood potassium be tested?

In some cases, the potassium level in the blood must be monitored on a regular basis. The examination is routinely performed in patients with cardiac arrhythmias. Potassium should also be tested in the following cases:

  • hypertension,
  • taking water tablets (diuretics),
  • conditions with diarrhea and vomiting,
  • regular consumption of caffeinated beverages or alcohol,
  • intense regular physical activity,
  • when renal failure is suspected  .

In addition, the doctor may order a test when there are symptoms that indicate abnormal levels of potassium in the body. 

  • night muscle cramps
  • muscle weakness,
  • heart disorders,
  • weakness.

Symptoms of excess and deficiency of potassium in the blood

Too much potassium in the blood is  hyperkalemia . In mild and moderate conditions, it is asymptomatic. In some cases, a person with too much potassium may experience:

  • sensory disturbances,
  • tingling around the mouth and tongue
  • Heart arythmia,
  • apathy
  • muscle weakness, 
  • muscle cramps.

This is a dangerous condition. In extreme cases, hyperkalemia leads to cardiac arrest and death. 

Low potassium levels are hypokalemia . Potassium levels that are too low can manifest as:

  • heart disorders,
  • high blood pressure
  • muscle weakness,
  • constipation,
  • nausea,
  • weakness,
  • urinary retention,
  • neurological disorders,
  • kidney disorders.

Too much potassium causes

Too much potassium in the blood, i.e., exceeding the norm of 5.0 mmol/ll, may occur due to:

  • kidney failure,
  • dehydration,
  • serious injuries, burns (destruction of red blood cells),
  • taking certain medications, e.g., non-steroidal anti-inflammatory drugs, beta-blockers, angiotensin converting enzyme inhibitors,
  • adrenal insufficiency
  • type 1 diabetes,
  • taking too many potassium supplements,
  • intravenous administration of excessive amounts of this element.

The most common cause of high blood potassium levels is kidney disease. Its excess is excreted from the body via urine, which is why a diet high in potassium-rich foods has no negative side effects. Only taking a lot of potassium supplements can lead to an overabundance of this element in the body. For humans, the toxic dose of potassium that causes poisoning and cardiac arrest is approximately 18 g per day.

Not enough potassium causes

Lowering the concentration of potassium below the norm, i.e., below 3.5 mmol/ll, most often occurs due to: 

  • diuretic therapy,
  • diarrhea and vomiting,
  • restrictive hunger strikes,
  • malnutrition (e.g. in anorexia),
  • a lot of sweating, 
  • chronic bowel diseases,
  • alcohol abuse,
  • ketoacidosis after administration of too much insulin in diabetic patients. 

Too much potassium—what to do? How to lower potassium

Disease is the most common cause of an increase in potassium in the body, so it is important to consult a doctor if an abnormal test result is received. To reduce potassium, it may be necessary to switch to a low-potassium diet by avoiding potassium-rich foods.

  • dried fruit (especially dried apricots),
  • figs, apples, dates, plums, bananas, currants, kiwi, citrus,
  • spinach leaves, kale,
  • cocoa,
  • Sunflower seeds,
  • beans, peas, lentils, soybeans,
  • tomatoes,
  • tomato concentrate,
  • an avocado,
  • almonds, hazelnuts, peanuts, pistachios,
  • fish,
  • wholegrain bread , 
  • coarse groats.

Not enough potassium—what to do? How to increase potassium

Potassium deficiency should be reported to a doctor, and treatment depends on medications and overall health. Other pharmacological agents may be prescribed, and potassium-rich foods should be included in the diet.