Chapter 4 - Endocrine System

on Tuesday, 25 March 2014. All News Items | Coding

This edition addresses some of the changes found in the Endocrine System. Please refer to your ICD-10-CM code book to gain familiarity with the codes as this chapter has significantly expanded. Then try to notice what documentation is missing from the records you are reviewing so that you can advise your physicians on what is needed for I-10. Once again, brushing up on your Anatomy and Physiology will also be crucial for this chapter.

The Endocrine System consists of glands of the body that secrete hormones into the blood stream. The word Hormone means to set in motion. Hormones start the process of change in:

  • Cells of specific body tissues
  • A single organ
  • A group of organs
  • All cells of the body

Did you know? There are other organs in the body that produce hormones but, that is not their main function, such as the heart and stomach.

What Changed in the Endocrine Chapter?

  • The diseases of the endocrine, nutritional, and metabolic diseases moved from Chapter 3 in I-9 to Chapter 4 in I-10
  • Certain disorders of the immune system have been moved out of the endocrine chapter and into Chapter 3 in I-10, "Diseases of the Blood, Blood Forming Organs, and Certain Disorders".
  • Gout was moved out of the Endocrine chapter and placed in Chapter 13, "Diseases of the Musculoskeletal System and Connective Tissue".
  • The type and cause of Cushing's Syndrome is now needed to assign the correct code.
  • More information is required to assign the correct code.
    • For example: Congenital Hypothyroidism- The code has been expanded and we now must know if there is documentation of a goiter in order to assign the appropriate code.
  • Diabetes Mellitus
  • Many code titles were revised

Notice below how the two code sets differ. Chapter 4 has more than doubled in size!


ICD-9-CM vs. ICD-10-CM

Chapter 3: Endocrine, Nutritional and Metabolic Diseases, and Immunity Disorders (240-279)Chapter 4: Endocrine, Nutritional and Metabolic Diseases (E00-E89)
Subchapters in ICD-9-CMSubchapters in ICD-10-CM
Disorders of Thyroid Glands (240-246) Disorders of Thyroid Gland (E00-E07)
Diabetes Mellitus (E08-E13)
Other Disorders of Glucose Regulation and Pancreatic Internal Secretion (E15-E16)
Disease of Other Endocrine Glands (249-259) Disorders of Other Endocrine Glands (E20-E35)
Intraoperative Complications of Endocrine Systems (E36)
Malnutrition (E40-E46)
Nutritional Deficiencies (260-269) Other Nutritional Deficiencies (E50-E64)
Overweight, Obesity, and Other Hyperalimentation (E65-E68)
Other Metabolic and Immunity Disorders (270-279) Metabolic Disorders (E70-E88)
Postprocedural Endocrine and Metabolic Complications and Disorders, NEC (E89)


It will be Easy to remember that the Endocrine chapter codes begin with the letter E!

Diabetes Mellitus
One of the major changes we see in I-10 is in the Endocrine System for Diabetes Mellitus. First of all, Diabetes has its own subchapter heading. And, in I-9, Diabetes was classified to one category, 250. Now there are 5 categories for Diabetes in I-10 and they are listed below:

  • E08, Diabetes Mellitus due to underlying condition
  • E09, Drug or chemical induces Diabetes Mellitus
  • E10, Type 1 Diabetes Mellitus
  • E11, Type 2 Diabetes Mellitus
  • E13, Other specified Diabetes Mellitus

Please note: "Use additional code to identify any insulin use (Z79.4)" is to be used with all diabetic cases except for Type 1. This additional insulin code is not assigned for Type 1 diabetic cases because insulin is required to maintain life.

The diabetic codes were expanded to reveal manifestations and complications of the disease via 4th or 5th characters instead of using an additional code to identify the manifestation.


Here is an example of how the diabetic codes have been expanded to include more information as compared to I-10:



Diabetes with Renal Manifestations, Type 1, Not Stated as Uncontrolled 250.41 Type 1 Diabetes Mellitus with Diabetic Nephropathy E10.21
Type 1 Diabetes Mellitus with Diabetic Chronic Kidney Disease E10.22
Type 1 Diabetes Mellitus with Other Diabetic Kidney Complication E10.29



Trying to code controlled and uncontrolled diabetes is no longer a coding issue! Even better, we can capture inadequately controlled, out of control, and poorly controlled diabetes and code it to Diabetes Mellitus, by type with hyperglycemia.



Hemoglobin A1c %

Estimated average glucose (mg/dL)

6% 126
7% 154
8% 183
9% 212
10% 240
11% 269
12% 298

Hemoglobin A1c: 7 is not a lucky number when it comes to Diabetes!

A1C is a blood test that will determine an average blood sugar reading over a period of 3 months and will reveal how well diabetes is being controlled. An A1c level of <7% is the goal for all diabetics. The higher the A1c level, the higher the risk of developing diabetic complications. The table shows an A1c with the corresponding estimated average glucose reading (eAG).

FYI - Secondary Diabetes Mellitus
This type of diabetes is caused by another disease or condition. The code title has changed in I-10 for Secondary Diabetes:

I-9 Secondary diabetes mellitus, 249.0
I-10 Diabetes due to underlying condition, E08


Pay attention to the code instructions under E08 when coding Secondary Diabetes:
Code first the underlying condition, such as:

  • Congenital Rubella (P35.0)
  • Cushing's Syndrome (E24.-)
  • Cystic Fibrosis (E84.-)
  • Malignant Neoplasm (C00-C96)
  • Malnutrition (E40-E46)
  • Pancreatitis and other diseases of the pancreas (K85.-, K86.-)

Use additional code to identify any insulin use (Z79.4)


Coding Guidelines for Diabetes Mellitus


Coding Guideline I.C.4.a., Diabetes Mellitus
The diabetes mellitus codes are combination codes that include the type of diabetes mellitus, the body system affected, and the complications affecting the body system. As many codes within a particular category as are necessary to describe all of the complications of the disease may be used. They should be sequenced based on the reason for a particular encounter. Assign as many codes from categories E08-E13 as needed to identify all of the associated conditions that the patient has.

Coding Guideline I.C.4.a.5 (a), Underdose of insulin due to insulin pump failure
An underdose of insulin due to an insulin pump failure should be assigned to a code from subcategory T85.6, Mechanical complication of other specified internal and external prosthetic devices, implants and grafts, that specifies the type of pump malfunction, as the principal or first-listed code, followed by code T38.3x6-, Underdosing of insulin and oral hypoglycemic [antidiabetic] drugs. Additional codes for the type of diabetes mellitus and any associated complications due to the underdosing should also be assigned.

Coding Guideline I.C.4.a.6., Secondary Diabetes Mellitus
Codes under categories E08, Diabetes mellitus due to underlying condition, and E09, Drug or chemical induced diabetes mellitus, identify complications/manifestations associated with secondary diabetes mellitus. Secondary diabetes is always caused by another condition or event (e.g., cystic fibrosis, malignant neoplasm of pancreas, pancreatectomy, adverse effect of drug, poisoning).

Coding Guideline I.C.4.a.6.b., Assigning and Sequencing Secondary Diabetes Codes and Its Causes
The sequencing of the secondary diabetes codes in relationship to codes for the cause of the diabetes is based on the Tabular List instructions for categories E08 and E09.

There are expanded instructions in Chapter 4 for coding late effects now called "Sequelae" in I-10.


Excludes 1 notes have been added to some categories between E50-E63 to indicate that the sequelae of the nutritional deficiency are assigned a code from category E64.


Article by Anita Meyers

Anita Meyers, RHIT, CCS, AHIMA-approved ICD-10 Trainer is an Inpatient Coding Professional at Medical Management Plus. Anita has over twenty-six years of experience in inpatient and outpatient coding including 17 years of work at AQAF reviewing inpatient and outpatient records from Alabama hospitals. In addition to reviewing records, she was the team leader in Beneficiary Services where she participated in case review activities, received and processed beneficiary complaints and handled fee-for-service denials for home health, hospice and skilled nursing facility services. Prior to joining the MMP, team, Anita left AQAF to become an inpatient contract coder and worked at various hospitals in central Alabama. In her current position, Anita is an integral part of the Inpatient Services at Medical Management Plus. You may contact Anita at This email address is being protected from spambots. You need JavaScript enabled to view it..

This material was compiled to share information. MMP is not offering legal advice. Every reasonable effort has been taken to ensure the information is accurate and useful.


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