2022 ICD-10-CM Code E73.9

Lactose intolerance, unspecified

Version 2021

Valid for Submission

ICD-10:E73.9
Short Description:Lactose intolerance, unspecified
Long Description:Lactose intolerance, unspecified

Code Classification

  • Endocrine, nutritional and metabolic diseases (E00–E90)
    • Metabolic disorders (E70-E88)
      • Lactose intolerance (E73)

E73.9 is a billable diagnosis code used to specify a medical diagnosis of lactose intolerance, unspecified. The code E73.9 is valid during the fiscal year 2022 from October 01, 2021 through September 30, 2022 for the submission of HIPAA-covered transactions.

The ICD-10-CM code E73.9 might also be used to specify conditions or terms like disaccharidase deficiency, intestinal disaccharidase deficiency, intolerance to lactose, lactase deficiency, malabsorption syndrome due to intolerance to lactose , sucrosuria, etc.

Unspecified diagnosis codes like E73.9 are acceptable when clinical information is unknown or not available about a particular condition. Although a more specific code is preferable, unspecified codes should be used when such codes most accurately reflect what is known about a patient's condition. Specific diagnosis codes should not be used if not supported by the patient's medical record.

Index to Diseases and Injuries

The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10 code(s). The following references for the code E73.9 are found in the index:

Approximate Synonyms

The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

Clinical Information

Convert E73.9 to ICD-9 Code

The General Equivalency Mapping (GEM) crosswalk indicates an approximate mapping between the ICD-10 code E73.9 its ICD-9 equivalent. The approximate mapping means there is not an exact match between the ICD-10 code and the ICD-9 code and the mapped code is not a precise representation of the original code.

Information for Patients


Lactose Intolerance

Lactose intolerance means that you cannot digest foods with lactose in them. Lactose is the sugar found in milk and foods made with milk. After eating foods with lactose in them, you may feel sick to your stomach. You may also have

Your doctor may do a blood, breath or stool test to find out if your problems are due to lactose intolerance.

Lactose intolerance is not serious. Eating less food with lactose, or using pills or drops to help you digest lactose usually helps. You may need to take a calcium supplement if you don't get enough of it from your diet, since milk and foods made with milk are the most common source of calcium for most people.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases


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Lactose intolerance

Lactose intolerance is an impaired ability to digest lactose, a sugar found in milk and other dairy products. Lactose is normally broken down by an enzyme called lactase, which is produced by cells in the lining of the small intestine.

Congenital lactase deficiency, also called congenital alactasia, is a disorder in which infants are unable to break down lactose in breast milk or formula. This form of lactose intolerance results in severe diarrhea. If affected infants are not given a lactose-free infant formula, they may develop severe dehydration and weight loss.

Lactose intolerance in adulthood is caused by reduced production of lactase after infancy (lactase nonpersistence). If individuals with lactose intolerance consume lactose-containing dairy products, they may experience abdominal pain, bloating, flatulence, nausea, and diarrhea beginning 30 minutes to 2 hours later.

Most people with lactase nonpersistence retain some lactase activity and can include varying amounts of lactose in their diets without experiencing symptoms. Often, affected individuals have difficulty digesting fresh milk but can eat certain dairy products such as cheese or yogurt without discomfort. These foods are made using fermentation processes that break down much of the lactose in milk.


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Gas in the Digestive Tract Overview of gas in the digestive tract, symptoms such as belching, bloating, and passing gas, and treatments or diet changes that can reduce gas symptoms.
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Lactose Intolerance Read about symptoms and management of lactose intolerance, a condition in which you have digestive symptoms after you consume foods or drinks that have lactose.
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Code History

  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016 (First year ICD-10-CM implemented into the HIPAA code set)