Blood test

Low phosphorus level in the blood

Blood test
Low phosphorus level in the blood
Last update: 18/03/2020

What is low phosphorus level in blood called?

  • Hypophosphatemia

What is the normal level of phosphorus in the blood?

If you need to know which are the sodium reference ranges or you require more information about the role of sodium in the blood, you can visit normal sodium level in the blood

What does a low blood phosphorus level mean?

Mild hypophosphatemia without any other symptom it is not a matter of concern. If phosphorus blood level is below 1.5 mg/dl or if you experience symptoms like fatigue or muscular weakness it can be a sign of problems related to bones, kidney or parathyroid gland.

Phosphorus blood values are usually given in mg/dl but sometimes you can see those values in mmol/l following the International System of Units (SI). In case your values are in mmol/l you can convert them using this tool:

  • Mild hypophosphatemia (2 - 2.5 mg/dL in adults):

    Phosphorus level in the blood is a bit low but it is not usually a cause for concern.

    If calcium is below the normal range and alkaline phosphatase is above normal range a vitamin D deficiency should be considered.

  • Moderate hypophosphatemia (1.5 - 2 mg/dL in adults):

    You phosphorus level in the blood is moderately low but probably you will not experience any clinical sign.

    Talk to your doctor and he will decide along with your medical history and any other test performed before if it is necessary to require additional tests and trials. Calcium blood level can give your doctor some clues.

  • Marked hypophosphatemia (1 - 1.5 mg/dL in adults):

    Marked hypophosphatemia requires follow-up. You can experience muscular weakness along with abnormal growth or swelling of bone.

    It is advisable to perform a phosphate urine test. If phosphate in urine is high (>3.2 mmol/dl) a kidney problem should be suspected. If phosphate in urine is low (< 3.2 mmol/dl) another condition, like malabsorption, should be suspected.

  • Severe hypophosphatemia (< 1 mg/dL in adults):

    Your phosphorus levels in the blood are too low and you need to look for urgent medical attention.

    If this level does not raise in 2 or 3 days you most probably will experience serious complications like cardiac arrhythmias, hemolytic anemia, seizures, respiratory failures, coma or sudden death.

Which factors can reduce phosphorus blood levels?

There are some circumstances or drugs than can reduce your phosphorus levels in the blood:

  • Alcohol
  • Vitamin D deficiency
  • Diarrhea
  • Pregnancy
  • Severe burns
  • Vomiting
  • Drugs
    • Antiepileptic drugs
      • Acetazolamide
      • Carbamazepine
    • Antituberculars
      • Isoniazid
    • Catecholamine
      • Epinephrine
    • Diuretics
      • Thiazides
    • Sugar substitute
      • Mannitol
    • Sex hormones
      • Estrogens
    • Salicylates

Which diseases can reduce your phosphorus blood levels?

Lower than normal levels of phosphorus in the blood can be due to:

What can I do to increase phosphorus blood levels?

If your phosphorus level in the blood is a bit low, the following tips can help you:

  • Increase vitamin D and phosphates in your diet. You can eat:
    • Dairy products: milk, yogurt, cheese, etc.
    • Fish: Carp, sardines, salmon, pollock
    • Meat: Pork, chicken or veal
    • Chocolate
    • Eggs
  • Phosphorus supplements: talk to your doctor to know if they are appropriate for you.

Where can I find more information about phosphorus in the blood?

You can visit our pages about:

Which values are considered a low phosphorus level in the blood?

The following values are considered to be below the normal range:

IMPORTANT: These levels are expressed in mg/dl. They are an example of a healthy man of about 45 years of age with no known disease, not taking any medication and with an appropriate intake of phosphorus in the diet. The ranges can be different depending on the laboratory or on your personal circumstances.

Mild hypophosphatemia
2.4 mg/dL2.3 mg/dL2.2 mg/dL2.1 mg/dL2 mg/dL   
Moderate hypophosphatemia
1.9 mg/dL1.8 mg/dL1.7 mg/dL1.6 mg/dL1.5 mg/dL   
Marked hypophosphatemia
1.4 mg/dL1.3 mg/dL1.2 mg/dL1.1 mg/dL1 mg/dL   
Severe hypophosphatemia
0.9 mg/dL0.8 mg/dL0.7 mg/dL0.6 mg/dL0.5 mg/dL0.4 mg/dL0.3 mg/dL0.2 mg/dL
0.1 mg/dL0 mg/dL      
Medically reviewed by Javier Muga Bustamante Ph.D. on 18/03/2020


  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 497.
  • Tietz. Fundamentals of Clinical Chemistry. Carl A. Burtis, Edward R. Ashwood, David E. Bruns, Barbara G. Sawyer. WB Saunders Company, 2008. Pag 717. ISBN: 978-0-7216-3865-2.
  • Common Terminology Criteria for Adverse Events (CTCAE). Version 4.0.Published: May 28, 2009. U.S. Department of health and human Services. Available on:
  • Fraser D, Jones G, Kooh SW, Radde IC. Calcium and phosphate metabolism. In: Tietz NW, ed. Fundamentals of clinical chemistry. Philadelphia:WB Saunders Company, 1987:706pp.

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