Medical Abbreviations Starting With a Number

This page lists 29 medical abbreviations starting with a Number, each with its full form and a plain-English meaning. Where one abbreviation has more than one common meaning, each meaning has its own row — context in the chart is what tells them apart. Terms flagged ⚠ Error-prone are on recognised error-prone lists and should be written out in full. Use the filter box to narrow this list, the search on the main guide to search all 5,715 entries, or jump to another letter:

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Abbreviation	Full form	What it means	Used in
1,25-(OH)2 vitamin D	1,25-dihydroxyvitamin D	Active form of vitamin D	Laboratory Endocrinology Renal & Nephrology
1-3-6	EHDI 1-3-6 benchmarks (screen diagnose intervene)	Hearing timeline goals by month of age	Pediatrics
14-3-3	14-3-3 protein (CSF)	Prion disease spinal fluid marker	Neurology Laboratory Infectious Disease
17-OHP	17-hydroxyprogesterone	Hormone measured when adrenal disorders are suspected	Endocrinology Laboratory Pediatrics
1:1	one-to-one observation	Continuous dedicated staff watching one patient	Nursing Psychiatry
1h GTT	one-hour glucose challenge test	First-step gestational diabetes screen	Obstetrics & Gynecology Laboratory
21-hydroxylase	21-hydroxylase deficiency (CAH)	Commonest adrenal hyperplasia enzyme defect	Pediatrics Endocrinology Laboratory
25-OH vitamin D	25-hydroxyvitamin D	Storage form of vitamin D measured to check vitamin D status	Laboratory Endocrinology
2g Na diet	two-gram sodium diet	Low-salt diet order	Nursing Cardiology Renal & Nephrology
3 Cs measles	three Cs of measles (cough coryza conjunctivitis)	Classic measles prodrome features	Pediatrics Infectious Disease
3% saline	three percent saline (hypertonic)	Concentrated sodium infusion	Emergency & Critical Care Prescription & Medication Orders Neurology
3D-CAM	3-minute Diagnostic Confusion Assessment Method	Quick delirium assessment	Neurology Emergency & Critical Care
3D-CRT	three-dimensional conformal radiation therapy	Radiation shaped by 3D planning scans	Hematology & Oncology Radiology & Imaging
3h GTT	three-hour glucose tolerance test	Confirmatory gestational diabetes test	Obstetrics & Gynecology Laboratory
4-point restraints	four-point restraints	Limb restraints at four points in severe agitation	Nursing Psychiatry Emergency & Critical Care
4AT	4 A's test	Rapid delirium and cognition screening tool	Psychiatry Neurology Vitals & Assessment
4F-PCC	four-factor prothrombin complex concentrate	Concentrate containing factors II, VII, IX and X	Hematology & Oncology Emergency & Critical Care
4Ts	4Ts score	Probability score for heparin-induced thrombocytopenia	Hematology & Oncology Laboratory
5'-NT	5-prime nucleotidase	Liver enzyme checked alongside alkaline phosphatase	Laboratory Gastroenterology
5-FU	fluorouracil	Chemotherapy drug used in gut and other cancers	Prescription & Medication Orders Hematology & Oncology
5-HIAA	5-hydroxyindoleacetic acid	Urine test used for carcinoid syndrome	Laboratory Endocrinology Gastroenterology
5150	5150 hold (California)	California involuntary psychiatric hold code	Psychiatry Emergency & Critical Care
5150 hold eval	72-hour hold evaluation	Assessment period under an involuntary hold	Psychiatry Emergency & Critical Care
6-MP	mercaptopurine	Leukemia and immune disease drug	Prescription & Medication Orders Hematology & Oncology
6-TG	thioguanine	Leukemia chemotherapy drug	Prescription & Medication Orders Hematology & Oncology
6MWT	six-minute walk test	Test measuring how far a person walks in six minutes	Respiratory
7+3	seven plus three induction	Classic AML induction: seven days of cytarabine plus three of anthracycline	Hematology & Oncology Prescription & Medication Orders
90-90 traction	ninety-ninety traction (femur)	Hip and knee bent traction for thigh fractures	Pediatrics Musculoskeletal Surgery
9HPT	Nine-Hole Peg Test	MS hand dexterity test	Neurology

Educational reference only. This guide is for learning and quick reference. Abbreviations vary between hospitals, countries and specialties, and some are discouraged because they can be misread. Always write and interpret orders using your own institution’s approved abbreviation list, and check anything unclear with the prescriber or your local policy.

Medical Abbreviations Starting With a Number

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