DRG 642
Medical DRGInborn and Other Disorders of Metabolism
What is MS-DRG 642?
MS-DRG 642 is a Medical Medicare Severity Diagnosis Related Group under Major Diagnostic Category 10 (MDC 10). It maps to 216 ICD-10-CM diagnosis codes. For FY 2026 it carries a relative weight of 1.4221 with a geometric mean length of stay of 3.4 days and an arithmetic mean of 4.6 days. Hospitals use this grouping to determine reimbursement for inpatient stays under Medicare.
FY 2026 Payment Data
Official values from Table 5 of the FY 2026 IPPS Final Rule (CMS).
Linked ICD-10-CM Diagnosis Mappings
- C96.5
Multifocal and unisystemic Langerhans-cell histiocytosis
BillableChapter 2 - C96.6
Unifocal Langerhans-cell histiocytosis
BillableChapter 2 - D81.30
Adenosine deaminase deficiency, unspecified
BillableChapter 3 - D81.31
Severe combined immunodeficiency due to adenosine deaminase deficiency
BillableChapter 3 - D81.32
Adenosine deaminase 2 deficiency
BillableChapter 3 - D81.39
Other adenosine deaminase deficiency
BillableChapter 3 - D81.5
Purine nucleoside phosphorylase [PNP] deficiency
BillableChapter 3 - D81.810
Biotinidase deficiency
BillableChapter 3 - D84.1
Defects in the complement system
BillableChapter 3 - E70.0
Classical phenylketonuria
BillableChapter 4 - E70.1
Other hyperphenylalaninemias
BillableChapter 4 - E70.20
Disorder of tyrosine metabolism, unspecified
BillableChapter 4 - E70.21
Tyrosinemia
BillableChapter 4 - E70.29
Other disorders of tyrosine metabolism
BillableChapter 4 - E70.30
Albinism, unspecified
BillableChapter 4 - E70.310
X-linked ocular albinism
BillableChapter 4 - E70.311
Autosomal recessive ocular albinism
BillableChapter 4 - E70.318
Other ocular albinism
BillableChapter 4 - E70.319
Ocular albinism, unspecified
BillableChapter 4 - E70.320
Tyrosinase negative oculocutaneous albinism
BillableChapter 4 - E70.321
Tyrosinase positive oculocutaneous albinism
BillableChapter 4 - E70.328
Other oculocutaneous albinism
BillableChapter 4 - E70.329
Oculocutaneous albinism, unspecified
BillableChapter 4 - E70.330
Chediak-Higashi syndrome
BillableChapter 4 - E70.331
Hermansky-Pudlak syndrome
BillableChapter 4 - E70.338
Other albinism with hematologic abnormality
BillableChapter 4 - E70.339
Albinism with hematologic abnormality, unspecified
BillableChapter 4 - E70.39
Other specified albinism
BillableChapter 4 - E70.40
Disorders of histidine metabolism, unspecified
BillableChapter 4 - E70.41
Histidinemia
BillableChapter 4 - E70.49
Other disorders of histidine metabolism
BillableChapter 4 - E70.5
Disorders of tryptophan metabolism
BillableChapter 4 - E70.81
Aromatic L-amino acid decarboxylase deficiency
BillableChapter 4 - E70.89
Other disorders of aromatic amino-acid metabolism
BillableChapter 4 - E70.9
Disorder of aromatic amino-acid metabolism, unspecified
BillableChapter 4 - E71.0
Maple-syrup-urine disease
BillableChapter 4 - E71.110
Isovaleric acidemia
BillableChapter 4 - E71.111
3-methylglutaconic aciduria
BillableChapter 4 - E71.118
Other branched-chain organic acidurias
BillableChapter 4 - E71.120
Methylmalonic acidemia
BillableChapter 4 - E71.121
Propionic acidemia
BillableChapter 4 - E71.128
Other disorders of propionate metabolism
BillableChapter 4 - E71.19
Other disorders of branched-chain amino-acid metabolism
BillableChapter 4 - E71.2
Disorder of branched-chain amino-acid metabolism, unspecified
BillableChapter 4 - E71.30
Disorder of fatty-acid metabolism, unspecified
BillableChapter 4 - E71.310
Long chain/very long chain acyl CoA dehydrogenase deficiency
BillableChapter 4 - E71.311
Medium chain acyl CoA dehydrogenase deficiency
BillableChapter 4 - E71.312
Short chain acyl CoA dehydrogenase deficiency
BillableChapter 4 - E71.313
Glutaric aciduria type II
BillableChapter 4 - E71.314
Muscle carnitine palmitoyltransferase deficiency
BillableChapter 4 - E71.318
Other disorders of fatty-acid oxidation
BillableChapter 4 - E71.32
Disorders of ketone metabolism
BillableChapter 4 - E71.39
Other disorders of fatty-acid metabolism
BillableChapter 4 - E71.40
Disorder of carnitine metabolism, unspecified
BillableChapter 4 - E71.41
Primary carnitine deficiency
BillableChapter 4 - E71.42
Carnitine deficiency due to inborn errors of metabolism
BillableChapter 4 - E71.43
Iatrogenic carnitine deficiency
BillableChapter 4 - E71.440
Ruvalcaba-Myhre-Smith syndrome
BillableChapter 4 - E71.448
Other secondary carnitine deficiency
BillableChapter 4 - E71.50
Peroxisomal disorder, unspecified
BillableChapter 4 - E71.510
Zellweger syndrome
BillableChapter 4 - E71.511
Neonatal adrenoleukodystrophy
BillableChapter 4 - E71.518
Other disorders of peroxisome biogenesis
BillableChapter 4 - E71.520
Childhood cerebral X-linked adrenoleukodystrophy
BillableChapter 4 - E71.521
Adolescent X-linked adrenoleukodystrophy
BillableChapter 4 - E71.522
Adrenomyeloneuropathy
BillableChapter 4 - E71.528
Other X-linked adrenoleukodystrophy
BillableChapter 4 - E71.529
X-linked adrenoleukodystrophy, unspecified type
BillableChapter 4 - E71.53
Other group 2 peroxisomal disorders
BillableChapter 4 - E71.540
Rhizomelic chondrodysplasia punctata
BillableChapter 4 - E71.541
Zellweger-like syndrome
BillableChapter 4 - E71.542
Other group 3 peroxisomal disorders
BillableChapter 4 - E71.548
Other peroxisomal disorders
BillableChapter 4 - E72.00
Disorders of amino-acid transport, unspecified
BillableChapter 4 - E72.01
Cystinuria
BillableChapter 4 - E72.02
Hartnup's disease
BillableChapter 4 - E72.03
Lowe's syndrome
BillableChapter 4 - E72.04
Cystinosis
BillableChapter 4 - E72.09
Other disorders of amino-acid transport
BillableChapter 4 - E72.10
Disorders of sulfur-bearing amino-acid metabolism, unspecified
BillableChapter 4 - E72.11
Homocystinuria
BillableChapter 4 - E72.12
Methylenetetrahydrofolate reductase deficiency
BillableChapter 4 - E72.19
Other disorders of sulfur-bearing amino-acid metabolism
BillableChapter 4 - E72.20
Disorder of urea cycle metabolism, unspecified
BillableChapter 4 - E72.21
Argininemia
BillableChapter 4 - E72.22
Arginosuccinic aciduria
BillableChapter 4 - E72.23
Citrullinemia
BillableChapter 4 - E72.29
Other disorders of urea cycle metabolism
BillableChapter 4 - E72.3
Disorders of lysine and hydroxylysine metabolism
BillableChapter 4 - E72.4
Disorders of ornithine metabolism
BillableChapter 4 - E72.50
Disorder of glycine metabolism, unspecified
BillableChapter 4 - E72.51
Non-ketotic hyperglycinemia
BillableChapter 4 - E72.52
Trimethylaminuria
BillableChapter 4 - E72.530
Primary hyperoxaluria, type 1
BillableChapter 4 - E72.538
Other specified primary hyperoxaluria
BillableChapter 4 - E72.539
Primary hyperoxaluria, unspecified
BillableChapter 4 - E72.59
Other disorders of glycine metabolism
BillableChapter 4 - E72.81
Disorders of gamma aminobutyric acid metabolism
BillableChapter 4 - E72.89
Other specified disorders of amino-acid metabolism
BillableChapter 4 - E72.9
Disorder of amino-acid metabolism, unspecified
BillableChapter 4 - E74.00
Glycogen storage disease, unspecified
BillableChapter 4 - E74.01
von Gierke disease
BillableChapter 4 - E74.02
Pompe disease
BillableChapter 4 - E74.03
Cori disease
BillableChapter 4 - E74.04
McArdle disease
BillableChapter 4 - E74.05
Lysosome-associated membrane protein 2 [LAMP2] deficiency
BillableChapter 4 - E74.09
Other glycogen storage disease
BillableChapter 4 - E74.20
Disorders of galactose metabolism, unspecified
BillableChapter 4 - E74.21
Galactosemia
BillableChapter 4 - E74.29
Other disorders of galactose metabolism
BillableChapter 4 - E74.4
Disorders of pyruvate metabolism and gluconeogenesis
BillableChapter 4 - E74.810
Glucose transporter protein type 1 deficiency
BillableChapter 4 - E74.818
Other disorders of glucose transport
BillableChapter 4 - E74.819
Disorders of glucose transport, unspecified
BillableChapter 4 - E74.820
SLC13A5 Citrate Transporter Disorder
BillableChapter 4 - E74.829
Other disorders of citrate metabolism
BillableChapter 4 - E74.89
Other specified disorders of carbohydrate metabolism
BillableChapter 4 - E74.9
Disorder of carbohydrate metabolism, unspecified
BillableChapter 4 - E75.21
Fabry (-Anderson) disease
BillableChapter 4 - E75.22
Gaucher disease
BillableChapter 4 - E75.240
Niemann-Pick disease type A
BillableChapter 4 - E75.241
Niemann-Pick disease type B
BillableChapter 4 - E75.242
Niemann-Pick disease type C
BillableChapter 4 - E75.243
Niemann-Pick disease type D
BillableChapter 4 - E75.244
Niemann-Pick disease type A/B
BillableChapter 4 - E75.248
Other Niemann-Pick disease
BillableChapter 4 - E75.249
Niemann-Pick disease, unspecified
BillableChapter 4 - E75.3
Sphingolipidosis, unspecified
BillableChapter 4 - E75.5
Other lipid storage disorders
BillableChapter 4 - E75.6
Lipid storage disorder, unspecified
BillableChapter 4 - E76.01
Hurler's syndrome
BillableChapter 4 - E76.02
Hurler-Scheie syndrome
BillableChapter 4 - E76.03
Scheie's syndrome
BillableChapter 4 - E76.1
Mucopolysaccharidosis, type II
BillableChapter 4 - E76.210
Morquio A mucopolysaccharidoses
BillableChapter 4 - E76.211
Morquio B mucopolysaccharidoses
BillableChapter 4 - E76.219
Morquio mucopolysaccharidoses, unspecified
BillableChapter 4 - E76.22
Sanfilippo mucopolysaccharidoses
BillableChapter 4 - E76.29
Other mucopolysaccharidoses
BillableChapter 4 - E76.3
Mucopolysaccharidosis, unspecified
BillableChapter 4 - E76.8
Other disorders of glucosaminoglycan metabolism
BillableChapter 4 - E76.9
Glucosaminoglycan metabolism disorder, unspecified
BillableChapter 4 - E77.0
Defects in post-translational modification of lysosomal enzymes
BillableChapter 4 - E77.1
Defects in glycoprotein degradation
BillableChapter 4 - E77.8
Other disorders of glycoprotein metabolism
BillableChapter 4 - E77.9
Disorder of glycoprotein metabolism, unspecified
BillableChapter 4 - E78.00
Pure hypercholesterolemia, unspecified
BillableChapter 4 - E78.010
Homozygous familial hypercholesterolemia [HoFH]
BillableChapter 4 - E78.011
Heterozygous familial hypercholesterolemia [HeFH]
BillableChapter 4 - E78.019
Familial hypercholesterolemia, unspecified
BillableChapter 4 - E78.1
Pure hyperglyceridemia
BillableChapter 4 - E78.2
Mixed hyperlipidemia
BillableChapter 4 - E78.3
Hyperchylomicronemia
BillableChapter 4 - E78.41
Elevated Lipoprotein(a)
BillableChapter 4 - E78.49
Other hyperlipidemia
BillableChapter 4 - E78.5
Hyperlipidemia, unspecified
BillableChapter 4 - E78.6
Lipoprotein deficiency
BillableChapter 4 - E78.70
Disorder of bile acid and cholesterol metabolism, unspecified
BillableChapter 4 - E78.79
Other disorders of bile acid and cholesterol metabolism
BillableChapter 4 - E78.81
Lipoid dermatoarthritis
BillableChapter 4 - E78.89
Other lipoprotein metabolism disorders
BillableChapter 4 - E78.9
Disorder of lipoprotein metabolism, unspecified
BillableChapter 4 - E79.1
Lesch-Nyhan syndrome
BillableChapter 4 - E79.2
Myoadenylate deaminase deficiency
BillableChapter 4 - E79.81
Aicardi-Goutieres syndrome
BillableChapter 4 - E79.82
Hereditary xanthinuria
BillableChapter 4 - E79.89
Other specified disorders of purine and pyrimidine metabolism
BillableChapter 4 - E79.9
Disorder of purine and pyrimidine metabolism, unspecified
BillableChapter 4 - E80.0
Hereditary erythropoietic porphyria
BillableChapter 4 - E80.1
Porphyria cutanea tarda
BillableChapter 4 - E80.20
Unspecified porphyria
BillableChapter 4 - E80.21
Acute intermittent (hepatic) porphyria
BillableChapter 4 - E80.29
Other porphyria
BillableChapter 4 - E80.3
Defects of catalase and peroxidase
BillableChapter 4 - E83.00
Disorder of copper metabolism, unspecified
BillableChapter 4 - E83.01
Wilson's disease
BillableChapter 4 - E83.09
Other disorders of copper metabolism
BillableChapter 4 - E83.10
Disorder of iron metabolism, unspecified
BillableChapter 4 - E83.110
Hereditary hemochromatosis
BillableChapter 4 - E83.111
Hemochromatosis due to repeated red blood cell transfusions
BillableChapter 4 - E83.118
Other hemochromatosis
BillableChapter 4 - E83.119
Hemochromatosis, unspecified
BillableChapter 4 - E83.19
Other disorders of iron metabolism
BillableChapter 4 - E83.30
Disorder of phosphorus metabolism, unspecified
BillableChapter 4 - E83.31
Familial hypophosphatemia
BillableChapter 4 - E83.32
Hereditary vitamin D-dependent rickets (type 1) (type 2)
BillableChapter 4 - E83.39
Other disorders of phosphorus metabolism
BillableChapter 4 - E83.822
ENPP1 deficiency causing autosomal recessive hypophosphatemic rickets type 2
BillableChapter 4 - E83.824
ABCC6 deficiency causing pseudoxanthoma elasticum
BillableChapter 4 - E83.89
Other disorders of mineral metabolism
BillableChapter 4 - E83.9
Disorder of mineral metabolism, unspecified
BillableChapter 4 - E88.01
Alpha-1-antitrypsin deficiency
BillableChapter 4 - E88.10
Lipodystrophy, unspecified
BillableChapter 4 - E88.11
Partial lipodystrophy
BillableChapter 4 - E88.12
Generalized lipodystrophy
BillableChapter 4 - E88.13
Localized lipodystrophy
BillableChapter 4 - E88.14
HIV-associated lipodystrophy
BillableChapter 4 - E88.19
Other lipodystrophy, not elsewhere classified
BillableChapter 4 - E88.2
Lipomatosis, not elsewhere classified
BillableChapter 4 - E88.40
Mitochondrial metabolism disorder, unspecified
BillableChapter 4 - E88.41
MELAS syndrome
BillableChapter 4 - E88.42
MERRF syndrome
BillableChapter 4 - E88.43
Disorders of mitochondrial tRNA synthetases
BillableChapter 4 - E88.49
Other mitochondrial metabolism disorders
BillableChapter 4 - E88.810
Metabolic syndrome
BillableChapter 4 - E88.811
Insulin resistance syndrome, Type A
BillableChapter 4 - E88.818
Other insulin resistance
BillableChapter 4 - E88.819
Insulin resistance, unspecified
BillableChapter 4 - E88.82
Obesity due to disruption of MC4R pathway
BillableChapter 4 - E88.89
Other specified metabolic disorders
BillableChapter 4 - E88.9
Metabolic disorder, unspecified
BillableChapter 4 - E88.A
Wasting disease (syndrome) due to underlying condition
BillableChapter 4 - H49.811
Kearns-Sayre syndrome, right eye
BillableChapter 7 - H49.812
Kearns-Sayre syndrome, left eye
BillableChapter 7 - H49.813
Kearns-Sayre syndrome, bilateral
BillableChapter 7 - H49.819
Kearns-Sayre syndrome, unspecified eye
BillableChapter 7