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Elevated Alkaline Phosphatase Levels

Elevated Alkaline Phosphatase Levels

Alkaline phosphatase is a hydrolase enzyme that is responsible for the release of phosphate from proteins and other molecules. This enzyme is found in the liver, bones, bile duct, lining of the intestine, kidney, and placenta, and it requires an alkaline pH to perform its normal functions. ALP can be evaluated by a routine blood test, and its level in the blood can get elevated due to a number of factors, ranging from pregnancy, bone growth to certain serious medical conditions.
Chandramita Bora
Last Updated: Apr 19, 2018
Did You Know!
► The normal reference range of alkaline phosphatase (ALP) is around 25 to 120 international units per liter (IU/L), in adults.
► In hemodialysis patients, an increased level of ALP is associated with higher risks of hospitalization and mortality.
► Many a time, alarmingly high ALP levels are observed in people diagnosed with Chronic Kidney Disease (CKD).

According to the National Kidney Foundation's 2012 Spring Clinical Meetings, high level of ALP is linked with reduced survival rate amongst hemodialysis (HD) patients. They concluded this by examining and following up with around 64 HD patients for a period of more than seven years. Every one unit increase in the alkaline phosphatase level anticipated a 0.5% increase in the fatality rate. The sampled population had a mean ALP level of 122 IU/L, and a median ALP level of 89 IU/L respectively, and increased levels (>104 IU/L) were present in 39% of them. The ALP enzyme directly correlated to the parathyroid hormone, calcium, and the time spent on dialysis.

Factors Leading to Elevated ALP

The level of this enzyme in the body is usually examined in the diagnosis of either liver or bone related diseases. Along with liver diseases, bile duct obstruction and gallbladder dysfunction can be the other factors causing a significant rise in its level. An examination of the level of this enzyme is a part of liver tests, as its higher levels can indicate liver dysfunction. It can also indicate biliary obstruction or obstruction of the bile duct, which can be caused by stones or sludge.

A few conditions that lead to an increase in the level of ALP include...

Bone conditions like:
  • Bone fractures
  • Bone metastases (first widely known signs in cancer patients)
  • Rheumatoid arthritis (joint inflammation)
  • Osteoporosis (abnormal loss of bone tissue)
  • Hyperparathyroidism (excessive production of parathyroid hormone)
  • Adrenal cortical hyperfunction (excess production of adrenal cortex hormones)
  • Rickets (vitamin D deficiency)
  • Osteomalacia (softening of bones)
  • Osteosarcoma (type of bone cancer)
  • Paget's disease (alteration of the bone tissue in the elderly)
Liver congestion and other liver diseases such as:
  • Fatty liver
  • Liver tumor
  • Liver malignancy
  • Hepatitis (liver inflammation due to a virus)
  • Cirrhosis (degenerative liver disease)
  • Cholestasis (flow of bile into the digestive tract is obstructed)
  • Cholecystitis (inflammation of the gallbladder)
  • Cholangitis (inflammation of the bile ducts)
  • Infection caused by Cytomegalovirus (CMV, which is a herpes virus)
Other factors:
  • Shingles (Herpes Zoster)
  • Crohn's disease (inflammatory bowel disease)
  • Androgenic steroids (a steroid hormone like testosterone)
  • Myocardial infarctions (Acute tissue damage in the heart)
  • Amyloidosis (disorder due to accumulation of amyloid in the body)
  • Sarcoidosis (enlargement of the lymph nodes in many parts of the body)
  • Congestive heart failure
  • Oral contraceptives
  • Hormonal contraception
Use of certain drugs like:
  • Phenytoin (a drug used to treat epilepsy)
  • Ranitidine (an antacid used for peptic ulcers, gastritis and esophageal reflux)
  • Erythromycin (effective against gram-positive bacteria)
  • Carbamazepine (CBZ) (a drug used for epilepsy, bipolar disorder and trigeminal neuralgia)
  • Verapamil (a drug used for hypertension, congestive heart failure, angina, migraine)
  • Allopurinol (a drug to treat gout or other conditions that produce excess uric acid)

Alkaline phosphatase is a product of a type of bone forming cells known as osteoblasts, and it can be related to bone growth. This enzyme's range/level is normally on the higher side amongst growing children as compared to adults. Hence, in children, it may not always be associated with liver or bone related diseases.

Likewise, during the later stage of pregnancy (third trimester), the enzyme level in a woman's body is around 125 - 250 IU/L. This elevation is not a matter of concern, as it is normal for the placenta to produce additional ALP. This enzyme is needed for the synthesis of proteins in the cells, and it has a vital part in the calcification of bones and cartilage.

ALP level is determined by examining a blood sample. It is very important to determine the exact reasons behind its increased levels. But, it can be quite difficult at times to find out whether a rise in the level of this enzyme is caused by a liver or bone disease. If it is found to be elevated along with other enzymes, then a liver disease can be responsible for such a situation.

As mentioned earlier, growing children, expecting mothers, and those taking certain medications can experience a rise in the level of alkaline phosphatase, even in the absence of any serious medical condition. But still, a considerable rise in its level should be looked into. It is advisable to consult an experienced physician to rule out the possibility of some alarming medical problems.

Disclaimer: This HealthHearty article is for informative purposes only, and should not be used as a replacement for expert medical advice.