Correct Coding for Hypothermia in ICD-10-CM

hypothermia coding in icd-10-cm
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** This post was reviewed and updated on November 17, 2023. **

Coding for hypothermia in ICD-10-CM starts with having a clear grasp of how the body reacts to this dangerous medical condition.

A Case of Hypothermia

My Uncle Jim lives in Maine, where the winters get exceptionally cold. Last year he needed to save some money, so he turned his heat down to 62 degrees. That decision almost cost him his life.

When Uncle Jim’s daughter, my cousin Julie, arrived at his house, he was only wearing a light t-shirt, and the place was “frigid,” she stated. Julie said her dad was shivering, pale, speaking slowly, and having trouble walking. She wrapped her dad in a blanket and dialed 911. It turned out that Uncle Jim had hypothermia.

What Is Hypothermia?

According to MedicineNet, hypothermia is a body temperature of less than 95 °F (35 °C). Hypothermia in newborns has a body temperature of 97.5 °F (36.4 °C). Hypothermia includes two major classifications, accidental hypothermia, and intentional hypothermia.

Accidental hypothermia usually occurs when a person is exposed to cold temperatures, and it causes the body temperature to drop. Intentional hypothermia is when the body temperature is lowered, usually for a medical procedure.

A person may become hypothermic while in cold water, getting cold in wet clothes, living in a cold home, and not having the appropriate dry clothing for protection.

Another name for hypothermia is systemic cold injury. 

Accidental Hypothermia

The focus of this article is on accidental hypothermia. Individuals of all ages can be diagnosed with accidental hypothermia, but newborns and the elderly are more likely to have cold temperature exposure.

According to the Mayo Clinic, accidental hypothermia is a medical emergency that occurs when the body loses heat faster than it can produce it, leading to a dangerously low body temperature. When the body temperature drops, organs such as the heart and nervous system cannot work correctly. Without treatment, hypothermia can lead to heart failure, respiratory failure, and eventually death.

Symptoms of Accidental Hypothermia

The first symptom an individual will likely experience as the temperature drops is shivering. Other symptoms that develop may come on gradually.


There are three grades of hypothermia, according to MedicineNet. The grades vary according to severity (mild, moderate, severe), and some physicians may not agree on grading or fixed temperatures. However, the following is a general list of symptoms for each grade as hypothermia progresses.

  • Mild hypothermia: core temperature 90-95 °F (32-35 °C) – shivering; cold, pale or blue-gray skin; lack of concern; poor judgment; mild unsteadiness in balance or walking; numb hands and fingers
  • Moderate hypothermia: core temperature 82-90 °F (28-32 °C) – problems performing simple tasks; slurred speech
  • Severe hypothermia: core temperature below 82 °F (28 °C) – muscles becoming stiff; slow pulse; breathing that is shallow and slower; weakness or sleepiness; extreme confusion; loss of consciousness; shivering ceases; coma that leads to death

Newborns, Infants, and Children

Newborns, infants, and young children have a larger surface area than their body weight. Hence, they lose body heat quicker than older children and adults and are more likely to develop hypothermia.

The temperature values for hypothermia are a bit different for infants and include the following:

  • Mild hypothermia or cold stress: core temperature 96.8-97.5 °F (36.0-36.4 °C)
  • Moderate hypothermia: core temperature 89.6-96.6 °F (32.0-35.9 °C)
  • Severe hypothermia: core temperature below 89.6 °F (32 °C)

Infants and young children have more difficulty communicating their symptoms with caregivers and medical providers. However, some of the signs of hypothermia to look for include the following:

  • rectal or armpit temperature below 97.5 °F (36.4 °C)
  • skin cold and red
  • lethargic
  • low energy
  • weak cry
  • cool extremities and abdomen
  • poor feeding
  • hypoglycemia (low blood sugar)
  • hypoxia (low oxygen level)
  • apneic episodes (breathing stops during sleep)
  • heart arrhythmias (irregular heartbeat)

Furthermore, according to ResearchGate, some newborns exhibit:

  • cyanosis (bluish skin color)
  • bradycardia (slow heart rate)
  • bradypnea (slow respiratory rate)
  • scleredema (thickening and hardening of the skin)
  • jaundice (yellow discoloration of skin and eyes)
  • vomiting
  • seizures
  • secondary infections

Chronic hypothermia can occur in some infants and children, and the symptoms may include:

  • weight loss
  • no weight gain
  • failure to thrive

Children and teenagers who can communicate tend to have symptoms similar to adults but may have combined symptoms of adults and children.

Functional Changes Associated with Hypothermia

When a person is exposed to cold temperatures, most heat loss escapes through the skin, and the lungs exhale the rest. The hypothalamus is the part of the brain that controls body temperature and responds to body temperature changes by bringing them back in line.

During normal metabolic processes, the body regulates the core temperature by creating heat, cooling, or conserving heat. Heat conservation is done by peripheral vasoconstriction and by behavior. Producing heat is done by shivering and increasing the levels of thyroxine and epinephrine.

As the body temperature falls, the core tries to warm itself as much as possible by keeping blood away from the skin and losing heat to the environment. The blood flow is directed to the heart, lungs, kidney, and brain, leading to possible frostbite of the fingers, toes, hands, feet, ears, and nose.

When the body temperature falls to about 95 °F (35 °C), the heart, nervous system, and other organs stop working correctly. This can result in heart and respiratory system failure.

Risk Factors

Persons at risk for hypothermia include:

  • Infants, children, and elderly without sufficient clothing, heating, or food
  • People with mental illness
  • People who spend a lot of time outdoors
  • People who walk on a body of water that is partially frozen
  • People in cold weather who are under the influence of drugs or alcohol
  • Some medications can put a person at risk

Medical conditions that may make it difficult for the body to regulate its internal temperature:

  • Diabetes
  • Spinal cord injuries
  • Hypothyroidism
  • Burns
  • Parkinson’s disease
  • Malnutrition

Diagnosing Hypothermia

Diagnosis is based on the patient’s history and physical exam and the patient’s core body temperature. An adult is considered to be hyperthermic if the body temperature is below 95 °F (35 °C). An infant, on the other hand, is considered to be hypothermic if the body temperature is 97.5 °F (36.4 °C).

Most cases of hypothermia are treated as medical emergencies and require immediate treatment. Bradycardia develops in some patients and is shown by an abnormal electrocardiogram (ECG or EKG).

Complications During Recovery

During recovery, complications may include:

  • pneumonia
  • heart arrhythmias
  • ventricular fibrillation
  • cardiac arrest
  • death

It can be challenging to determine death in a hypothermic patient. Death should not be pronounced in a patient who appears to have suffered a cardiac arrest or as a result of hypothermia until they are rewarmed to 95 °F (35 °C).  

Video on How Hypothermia Kills

Here is a 3-minute video explaining hypothermia.

Coding For Hypothermia in ICD-10-CM

When assigning codes for accidental hypothermia in ICD-10-CM, the coder should consider whether the patient is a newborn or an older person.

Older children, teens, and adults diagnosed with hypothermia are reported with codes from Chapter 19. Injury, poisoning, and certain other consequences of external causes (S00-T88), Section T66-T78. Other and unspecified effects of external causes. Codes are further classified as to the episode of care (A for initial, D for subsequent, S for sequela).

A newborn diagnosed with hypothermia is reported with a code from Chapter 16. Certain conditions originating in the perinatal period (P00-P96) under the section named Conditions involving the integument and temperature regulation of newborn (P80-P83). Codes in this chapter include conditions that have their origin in the fetal or perinatal period (before birth through the first 28 days after birth) even if morbidity occurs later.

ICD-10-CM Coding Practice

Let’s look at a couple of coding scenarios.

hypothermia in adults ICD-10-CM codes

Example #1

A 56-year-old female was brought to the ER after being found outside her home unconscious. Her son states the patient had been outdoors shoveling her driveway for about an hour, and the temperature was only 4 degrees Fahrenheit. The patient was wearing only a light jacket and gloves and had nothing covering her head. Her blood-alcohol level was 120 mg/100 ml. The patient was admitted with a diagnosis of hypothermia, superficial frostbite of bilateral ear lobes, and acute alcohol intoxication.

The ICD-10-CM codes that should be assigned are:

  • T68.XXXA, Hypothermia, initial encounter
  • T33.011A, Superficial frostbite of right ear, initial encounter
  • T33.012A, Superficial frostbite of left ear, initial encounter
  • F10.129, Alcohol abuse with intoxication, unspecified
  • Y90.6, Blood alcohol level of 120-199 mg/100 ml
  • X31.XXXA, Exposure to excessive natural cold, initial encounter

Now let’s discuss how we came up with these codes.

The documentation states the diagnoses are hypothermia, superficial frostbite of bilateral ear lobes, and acute alcohol intoxication, so we need to be sure to assign for these conditions.

Hypothermia in adults

First, we know the patient is an adult, and the cause of the hypothermia is cold weather, so it’s accidental. In the ICD-10-CM Index, look up Hypothermia (accidental) T68. In the Tabular, we can verify our correct code as:

T68.XXXA, Hypothermia, initial encounter

Inclusion terms: Accidental hypothermia; Hypothermia NOS

An instructional note at T68 states, “The appropriate 7th character (A, D, S) is to be added to code T68.” This is an initial encounter where the patient is receiving active treatment, so the appropriate 7th character is “A.”

7th character “D” (subsequent encounter) is used after active treatment has been completed and routine care is provided during the healing or recovery phase.

7th character “S” (sequela) is used for complications or conditions that arise as a direct result of a condition.

The ICD-10-CM Official Guidelines for Coding and Reporting indicate, “While the patient may be seen by a new or different provider over the course of treatment for an injury, assignment of the 7th character is based on whether the patient is undergoing active treatment and not whether the provider is seeing the patient for the first time.”

Additional instructional notes at T68:

Use additional code to identify the source of exposure:

  • Exposure to excessive cold of man-made origin (W93)
  • Exposure to excessive cold of natural origin (X31)


  • hypothermia following anesthesia (T88.51)
  • hypothermia not associated with low environmental temperature (R68.0)
  • hypothermia of newborn (P80.-)

An Excludes1 note indicates if any of the following are documented, they need to be assigned a different code than T68.XXXA:

  • hypothermia following anesthesia (T88.51)
  • hypothermia not associated with low environmental temperature (R68.0)
  • hypothermia of newborn (P80.-).

Excludes2: frostbite (T33-T34)

An Excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions simultaneously.


Looking in the Tabular under Frostbite (T33-T34), frostbite is classified into superficial frostbite (T33) and frostbite with tissue necrosis (T34). The patient has bilateral superficial frostbite of the right and left earlobes. The codes are listed in T33.0 superficial frostbite of head with specific codes T33.011 and T33.012.

These codes require a 7th character for the episode of care. Therefore, “A” must be added to each code to indicate active treatment.

  • T33.011A, Superficial frostbite of right ear, initial encounter
  • T33.012A, Superficial frostbite of left ear, initial encounter

alcohol intoxication and Blood Alcohol level

Look in the Index under Alcohol, alcoholic, alcohol-induced/intoxication (acute) (without dependence), F10.129. We can verify this code In the Tabular as:

F10.129, Alcohol abuse with intoxication, unspecified

Excludes1: alcohol dependence (F10.2-)
alcohol use, unspecified (F10.9-)

Use additional code for blood alcohol level, if applicable (Y90.-)

The documentation indicates the patient’s blood-alcohol level was 120 mg/100 ml, so we need to assign a code for it.

Going directly to Y90.- in the Tabular, we can see that the correct code is:

Y90.6, Blood alcohol level of 120-199 mg/100 ml

You will see the note at Y90 that states, “Code first any associated alcohol-related disorders (F10)”. So that helps us with our sequencing. F10.129 is sequenced first, followed by Y90.6.

Exposure to Cold Weather

As the instructional note stated at T68, we need to assign a code from X31 for exposure to excessive cold of natural origin. Turning to X31 in the Tabular, we can see that this code also requires a 7th character with “X” as the placeholder, along with an “A” to indicate an initial encounter, making the correct code:

X31.XXXA, Exposure to excessive natural cold, initial encounter

Inclusion terms: Excessive cold as the cause of chilblains NOS; Excessive cold as the cause of immersion foot or hand; Exposure to cold NOS; Exposure to weather conditions


  • cold of man-made origin (W93.-)
  • contact with or inhalation of dry ice (W93.-)
  • contact with or inhalation of liquefied gas (W93.-)

Sequencing of External Cause codes

External cause of morbidity codes (V00-Y99) should never be sequenced as the first-listed or principal diagnosis, according to the ICD-10-CM Coding Guidelines. Therefore, Y90.6 and X31.XXXA are assigned as secondary codes.

Did I mention to be sure to read the Excludes1 and Excludes2 notes? Please read all the instructional notes because they all mean something.

hypothermia in newborns ICD-10-CM codes

Example #2

The patient is a 36-week gestational-age female newborn infant brought in today after being born outside of a shopping mall on a cold -11.2 °F (-24 °C) winter day in Deering, North Dakota. History showed no prenatal care had been given. The infant was found abandoned and gasping, with a heart rate of 50 beats/minute, and was immediately brought to the ER. She was noted to have bradycardia and apnea, with a rectal temperature of 82.22 °F (27.9 °C). The patient was diagnosed with severe hypothermia. Intubation and CPR were immediately performed.

This is a newborn being diagnosed with severe hypothermia.

Hypothermia in newborn

To locate the code in the ICD-10-CM Index, see Hypothermia (accidental), neonatal, severe (chronic) (Cold injury syndrome), P80.0. In the Tabular, this code can be verified as:

P80.0, Cold injury syndrome

Inclusion terms: Severe and usually chronic hypothermia associated with a pink flushed appearance, edema, and neurological and biochemical abnormalities

Codes from this chapter are only for use on newborn records, never on maternal records.

Other codes listed in this section are:

  • P80.8, Other hypothermia of newborn (mild hypothermia of newborn)
  • P80.9, Hypothermia of newborn, unspecified

Bradycardia and apnea should not be assigned as secondary codes because these symptoms are integral to hypothermia.

coding for hypothermia in ICD-10-CM

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I wrote this article and had it first published in BC Advantage/ under the title, “Baby, It’s Cold Outside, and That Can Kill You.” It is reprinted here with their permission. 

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