Chapter 4: Endocrine, nutritional and metabolic diseases (E00–E89)

Hormone, nutrition and metabolism disorders: diabetes and its complications, thyroid disease, high cholesterol, obesity, gout, dehydration and vitamin deficiencies.

Chapter 4 spans codes E00–E89 in the FY2027 ICD-10-CM tabular list. This guide explains 51 of its most common codes — select a code for its official description, a plain-English explanation and a note on when the code is used.

ICD-10 Chapter 4: Endocrine, Nutritional & Metabolic — illustrative image

Codes in this chapter

Code	Official description	In plain words
E03.9	Hypothyroidism, unspecified	Hypothyroidism is an underactive thyroid gland, slowing metabolism and causing tiredness, weight gain and cold sensitivity.
E04.1	Nontoxic single thyroid nodule	A single lump (nodule) in the thyroid gland that is not overactive; most are benign.
E04.9	Nontoxic goiter, unspecified	Goitre is an enlargement of the thyroid gland that is not caused by overactivity or inflammation.
E05.90	Thyrotoxicosis, unspecified without thyrotoxic crisis or storm	Thyrotoxicosis means excess thyroid hormone in the body, speeding up metabolism, without a documented crisis.
E06.3	Autoimmune thyroiditis	Autoimmune thyroiditis (Hashimoto's) is immune attack on the thyroid, gradually making it underactive.
E10.65	Type 1 diabetes mellitus with hyperglycemia	Type 1 diabetes in which blood glucose is documented as running high (hyperglycaemia).
E10.9	Type 1 diabetes mellitus without complications	Type 1 diabetes is an autoimmune condition in which the pancreas stops making insulin, so blood glucose rises.
E11.10	Type 2 diabetes mellitus with ketoacidosis without coma	Diabetic ketoacidosis is a dangerous complication of type 2 diabetes in which the body produces acidic ketones.
E11.21	Type 2 diabetes mellitus with diabetic nephropathy	Diabetic nephropathy is kidney damage caused by type 2 diabetes affecting the kidneys' filtering units.
E11.22	Type 2 diabetes mellitus with diabetic chronic kidney disease	Type 2 diabetes occurring together with chronic kidney disease, coded alongside the kidney stage code.
E11.319	Type 2 diabetes mellitus with unspecified diabetic retinopathy without macular edema	Diabetic retinopathy is damage to the blood vessels of the retina at the back of the eye caused by type 2 diabetes.
E11.36	Type 2 diabetes mellitus with diabetic cataract	A cataract (clouding of the eye's lens) caused by long-standing type 2 diabetes.
E11.42	Type 2 diabetes mellitus with diabetic polyneuropathy	Diabetic polyneuropathy is widespread nerve damage from type 2 diabetes, usually causing numbness and pain in the feet.
E11.51	Type 2 diabetes mellitus with diabetic peripheral angiopathy without gangrene	Diabetic peripheral angiopathy is narrowing of the leg arteries caused by type 2 diabetes, without gangrene.
E11.610	Type 2 diabetes mellitus with diabetic neuropathic arthropathy	Diabetic Charcot joint is progressive damage and deformity of a foot joint caused by nerve damage from type 2 diabetes.
E11.621	Type 2 diabetes mellitus with foot ulcer	A foot ulcer (open sore) occurring as a complication of type 2 diabetes, usually over a pressure area.
E11.649	Type 2 diabetes mellitus with hypoglycemia without coma	Low blood glucose (hypoglycaemia) occurring in a person with type 2 diabetes, without coma.
E11.65	Type 2 diabetes mellitus with hyperglycemia	Type 2 diabetes in which blood glucose is documented as running high (hyperglycaemia).
E11.69	Type 2 diabetes mellitus with other specified complication	Type 2 diabetes occurring with another specified complication not separately listed in the diabetes series.
E11.9	Type 2 diabetes mellitus without complications	Type 2 diabetes is a long-term condition in which the body resists insulin and gradually makes too little, raising blood glucose.
E16.2	Hypoglycemia, unspecified	Hypoglycaemia means abnormally low blood glucose, causing sweating, shaking, confusion and, if severe, collapse.
E21.0	Primary hyperparathyroidism	Primary hyperparathyroidism: an overactive parathyroid gland releases too much parathyroid hormone, raising blood calcium.
E21.3	Hyperparathyroidism, unspecified	Hyperparathyroidism is overactivity of the parathyroid glands, raising blood calcium levels.
E22.1	Hyperprolactinemia	Hyperprolactinaemia is a raised level of the hormone prolactin, which can affect periods, fertility and milk production.
E23.0	Hypopituitarism	Hypopituitarism is underactivity of the pituitary gland, reducing several hormones that control other glands.
E24.9	Cushing's syndrome, unspecified	Cushing's syndrome is the effect of too much cortisol hormone over time, causing weight gain, skin and muscle changes.
E26.9	Hyperaldosteronism, unspecified	Hyperaldosteronism is excess production of aldosterone by the adrenal glands, raising blood pressure and lowering potassium.
E27.40	Unspecified adrenocortical insufficiency	Adrenocortical insufficiency means the adrenal glands do not make enough steroid hormones, including cortisol.
E28.2	Polycystic ovarian syndrome	Polycystic ovary syndrome (PCOS) is a hormonal condition affecting ovulation, periods, and androgen levels.
E29.1	Testicular hypofunction	Testicular hypofunction means the testes produce too little testosterone (and sometimes too few sperm).
E34.9	Endocrine disorder, unspecified	A disorder of an endocrine (hormone) gland recorded without further detail.
E53.8	Deficiency of other specified B group vitamins	Deficiency of specified B-group vitamins other than B12 and folate, which support nerves, blood and energy metabolism.
E55.9	Vitamin D deficiency, unspecified	Vitamin D deficiency means too little vitamin D, important for bones, muscles and immune function.
E66.01	Morbid (severe) obesity due to excess calories	Morbid (severe) obesity due to excess calorie intake: a body mass index in the highest range with serious health risk.
E66.3	Overweight	Overweight means a body mass index above the healthy range but below the obesity range.
E66.9	Obesity, unspecified	Obesity is a long-term condition of excess body fat that raises the risk of diabetes, heart disease and joint problems.
E78.00	Pure hypercholesterolemia, unspecified	Pure hypercholesterolaemia is a raised level of cholesterol in the blood without other lipid abnormalities specified.
E78.1	Pure hyperglyceridemia	Pure hypertriglyceridaemia is a raised level of triglyceride fats in the blood.
E78.2	Mixed hyperlipidemia	Mixed hyperlipidaemia is a combination of raised cholesterol and raised triglycerides in the blood.
E78.5	Hyperlipidemia, unspecified	Hyperlipidaemia means raised levels of fats (lipids) such as cholesterol or triglycerides in the blood.
E79.0	Hyperuricemia without signs of inflammatory arthritis and tophaceous disease	A raised uric acid level in the blood without signs of gouty arthritis or urate stones.
E83.51	Hypocalcemia	Hypocalcaemia is a lower-than-normal level of calcium in the blood, which can cause tingling, cramps and spasms.
E83.52	Hypercalcemia	Hypercalcaemia is a higher-than-normal level of calcium in the blood, often from overactive parathyroid glands.
E87.1	Hypo-osmolality and hyponatremia	Hyponatraemia is a lower-than-normal sodium level in the blood, usually reflecting excess water relative to sodium.
E87.20	Acidosis, unspecified	Acidosis is an excess of acid in the body's fluids, from metabolic or other causes not further specified.
E87.22	Chronic metabolic acidosis	Chronic metabolic acidosis is a long-term excess of acid in the blood, most often seen with chronic kidney disease.
E87.5	Hyperkalemia	Hyperkalaemia is a higher-than-normal potassium level in the blood, which can affect the heart's rhythm.
E87.6	Hypokalemia	Hypokalaemia is a lower-than-normal potassium level in the blood, which can cause weakness and rhythm problems.
E87.70	Fluid overload, unspecified	Fluid overload means excess fluid in the body, causing swelling and sometimes breathlessness; the type is not specified.
E87.8	Other disorders of electrolyte and fluid balance, not elsewhere classified	Other disorders of the balance of salts (electrolytes) and fluid in the body not classified elsewhere.
E88.810	Metabolic syndrome	Metabolic syndrome is a cluster of raised blood pressure, blood sugar and waist size with abnormal blood fats.

This guide explains ICD-10-CM codes in plain language for patients, students and other readers. It is educational information only — not coding, billing or medical advice. The code recorded for any real encounter is assigned from the full clinical documentation by the treating team and qualified coders, and only they can decide which code fits a specific case.

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