| GABAP | Gabapentin Level | — |
| GDU | Gadolinium, 24 Hour, Urine | — |
| GDLM | Gadolinium, Serum | — |
| GA1PU | Galactose-1-Phosphate Uridyltransferase | — |
| GAL1PH | Galactose-1-Phosphate, Erythrocytes | — |
| GALEC3 | Galectin-3 | — |
| GGT | Gamma GT | Kinetic Colorimetric Method |
| GHBS | Gamma Hydroxybutyric Acid, Serum | — |
| GPS | Gammopathy Panel, Serum | — |
| GM1A | Ganglioside (GM1) Antibodies, IgG and IgM | — |
| GAES | Ganglioside Antibodies Evaluation, Serum | — |
| GARLIC | Garlic IgE | — |
| GAS | Gastrin | — |
| GCCTM | GC/Chlamydia by RNA | — |
| GCCU | GC/Chlamydia RNA Urine | — |
| VCGV1 | General Viral Culture, Non-Respiratory | — |
| VCRES | General Viral Culture, Respiratory | — |
| GENTP | Gentamicin, Peak | — |
| GENTR | Gentamicin, Random | — |
| GENTT | Gentamicin, Trough | — |
| GD0 | Gestational Diabetes Screen | Enzymatic Hexokinase Method |
| GDC | Gestational Diabetes Screen (2 specimens) | Enzymatic Hexokinase Method |
| GHBU | GHB, Urine | — |
| GIPARA | GI Parasite Panel by PCR | — |
| GIPNR | GI Pathogen Panel PCR | Film Array mutiplexed PCR |
| GIPPRPS | GI Pathogen Panel PCR, w/reflex | Film Array mutiplexed PCR |
| GLAM | Giardia Antigen by EIA | — |
| GIARA | Giardia lamblia Antibodies, IgG, IgM, and IgA | — |
| GLID | Gliadin, IgG & IgA | — |
| AGLO | Glomerular Basement Membrane Antibody, IgG | — |
| GGON | Glucagon | — |
| GLUC | Glucose | Enzymatic Hexokinase Method |
| GT2G | Glucose Tolerance 2 Hrs (Gestational) | Enzymatic Hexokinase Method |
| GT2 | Glucose Tolerance 2 Hrs (Non-OB) | Enzymatic Hexokinase Method |
| GTG | Glucose Tolerance 3 Hrs (Gestational) | Enzymatic Hexokinase Method |
| GT3 | Glucose Tolerance 3 Hrs (Non-OB) | Enzymatic Hexokinase Method |
| GTG4hour | Glucose Tolerance 4 Hrs (Gestational) | Enzymatic Hexokinase Method |
| GT4 | Glucose Tolerance 4 Hrs (Non-OB) | Enzymatic Hexokinase Method |
| GT5 | Glucose Tolerance 5 Hrs (Non-OB) | Enzymatic Hexokinase Method |
| UGL | Glucose Urine, Random | — |
| G6PR | Glucose-6-Phosphate Dehydrogenase (G6PD) | — |
| BGLU | Glucose, Body Fluid | Enzymatic Hexokinase Method |
| CGLU | Glucose, CSF | — |
| UGLUB | Glucose, Urine, 24 Hr. | — |
| GAD | Glutamic Acid Decarboxylase (GAD) Antibody | — |
| GD65S | Glutamic Acid Decarboxylase (GAD65) Antibody Assay, Serum | — |
| GLUTT | Glutathione, Total | — |
| GLUTEN | Gluten IgE | — |
| GLYCA | GlycA | Nuclear Magnetic Resonance (NMR) |
| GLCM | GlycoMark (1,5 Anhydroglucitol) Quant, Serum or Plasma | — |
| FGNDR | Gonadotropin Releasing Hormone | — |
| GRAMR | Gram Stain | — |
| GS | Gram Stain | — |
| GRAPE | Grape IgE | — |
| GRPFRT | Grapefruit IgE | — |
| GRNBN | Green Bean (String) IgE | — |
| GBSP | Group B Strep Screen by RT-PCR | — |
| GDF15 | Growth Differentiation Factor 15, Plasma | — |
| GHRIA | Growth Hormone, RIA | Double Antibody Radioimmunoassay (RIA) |
