"...all doctors should be able to diagnose and treat nutritional deficiencies."
Royal College of Physicians. Nutrition and Patients: A Doctor's Responsibility. London 2002
This page has been printed from the www.stewartnutrition.co.uk web site.
Nutritional Tests
Please read this before reviewing the table.
Laboratory tests of nutritional status are an important part of making a nutritional assessment. However with the rapid increase in both the availability and popularity of many such tests it should be remembered that diagnosis is made from the history (of the person’s complaint, dietary intake and risk factors), by clinical examination and then by appropriate use of laboratory or other tests. Without the first two components no logical decision about the choice of tests and their interpretation can be made.
The tests listed in the two accompanying tables are those that are in most common use and the majority have been used in the National Diet and Nutrition Surveys, NDNS, over the last fifteen years. The ranges quoted may vary from laboratory to laboratory. Those who are taking blood samples should note that there may be specific instructions for the patient prior to the test as well as for sample collection and handling, laboratory analysis and interpretation of the result. This is particularly true for trace elements, especially zinc (see www.izincg.org/pdf/English_brief2.pdf ) and vitamin A.
Some tests may require the involvement of a regional or specialist laboratory, which may be in the NHS or in the private sector.
Laboratory Tests of Nutritional Status - Minerals |
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| Test and Normal Range |
Likely Availability | National Diet and Nutrition Survey | ||
| Local NHS Hospital | Specialist Laboratory | Tested in NDNS* | Prevalence of deficiency on testing in NDNS populations |
|
| Anaemia - Haemoglobin <12.0 – 16.0 g/dl - women <13.0 – 17.0 g/dl - men [WHO normal ranges] |
Yes | No | Yes | Anaemia in: 8% of women aged 19-64 yrs 10% of free-living elderly 40% of institutionalised elderly |
| Iron Serum ferritin <15.0 umol/l |
Yes | No | Yes | 12% of women aged 19-49 yrs 8% of free-living elderly 10% of institutionalised elderly |
| Zinc Plasma 10.0 - 20.0 umol/l |
Possibly | Yes | Yes** | 2% of free-living elderly 9% of institutionalised elderly |
| Manganese Serum 9.0-25.0 umol/l |
No | Yes | No | Uncertain, probably rare |
| Copper Serum <11.0 - 25.1 umol/l |
Possibly | Yes | No | Very rare but possible |
| Selenium Plasma 0.29 - 0.91 umol/l |
Unlikely | Yes | Yes** | Severe deficiency is very rare but the prevalence of mild deficiency is unknown |
| Chromium Serum 6.2 - 16.7 nmol/l |
No | Yes | No | Prevalence of mild deficiency appears to rise with increasing age |
| Iodine Spot Urine >50 ug/l |
Unlikely | Possibly | No | Severe deficiency is very rare but the prevalence of mild deficiency is unknown |
| Magnesium Serum 0.75 - 0.95 mmol/l Red cell 2.08 - 3.0 mmol/l |
Possible Unlikely |
Yes Yes |
No No |
Low if deficient or metabolic disturbance Low in some situations |
| Calcium Bone Mineral Density Serum <2.15 mmol/l |
Yes Yes |
Yes Yes |
No Yes** |
Needed to diagnose osteoporosis Serum value is not a measure of status. Low levels are due to metabolic problems |
| Phosphate Serum <0.8 mmol/l |
Yes | Yes | No | Rare unless very unwell |
| Sodium Serum <135 mmol/l |
Yes | Yes | No | Deficiency is rare. Low serum level indicates metabolic disturbance |
| Potassium Serum <3.5 mmol/l |
Yes | Yes | No | Low serum levels usually indicate deficiency. Low intake is common in the elderly |
* National Diet and Nutrition Surveys of British Adults and the Elderly
** Measured in the NDNS of the elderly 65 years and over but not in adults
Laboratory Tests of Nutritional State – Vitamins |
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| Test and Normal Range | Likely Availability | National Diet and Nutrition Survey | ||
| Local NHS Hospital | Specialist Laboratory | Tested in NDNS* | Prevalence of deficiency on testing in NDNS populations |
|
| Vitamin A
Serum retinol |
Yes | Yes | Yes | <1% of adults <1% of all elderly |
| Vitamin B1-Thiamin ETKAC^ >1.25 |
Possibly | Yes | Yes | Increased enzyme activation coefficient 1% of adults 8% of free-living elderly 14% of institutionalised elderly |
| Vitamin B2 - Riboflavin EGRAC^ >1.3 [clinical significance uncertain] |
No | Yes | Yes | Increased enzyme activation coefficient 66% of adults 41% of free-living elderly 35% of institutionalised elderly |
| Vitamin B3 | No | Possibly | No | Uncertain, but probably very low |
| Vitamin B5 | No | No | No | Deficiency is considered to be very rare |
| Vitamin B6 EAATAC^ >2.0 [clinical significance uncertain] |
No | Yes | Yes | Increased enzyme activation coefficient 11% of adults Not measured in the elderly |
| Folate Serum >7.0nmol/l Red cell >350nmol/l |
Yes Yes |
Yes Yes |
Yes Yes |
Serum folate low in: < 1% or adults, 15% of the elderly Red cell folate low in: 5% of adults, 29% of the elderly |
| Vitamin B12 Serum 118 - 750 pmol/l |
Yes | Yes | Yes | Serum vitamin B12 low in: 3% of adults 6% of free-living elderly 12% of institutionalised elderly |
| Biotin | No | Yes | No | Deficiency is rare but possible |
| Vitamin C Plasma vitamin C >11.0umol/l |
Yes | Yes | Yes | Plasma vitamin C low in: 4% of adults 14% of free-living elderly 41% of institutionalised elderly |
| Vitamin D Plasma 25, hydroxy- Vitamin D 25..0 - 200 nmol/l |
Possibly | Yes | Yes | Plasma vitamin D low in: 14% of adults 8% of free-living elderly 37% of institutionalised elderly |
| Vitamin E Plasma alpha-tocopherol to cholesterol ratio <2.25umol/mmol |
Unlikely | Yes | Yes | Vitamin E status was low in: 1% of adult men and 2% of adult women. Not measured in the elderly |
| Vitamin K | Assessed indirectly by INR | Possibly | No | Status not assessed |
^ Tests of vitamins B1, B2 and B6 involved erythrocyte enzyme activation and calculation respectively of:
Erythrocyte Transketolase Activation Coefficient, ETKAC
Erythrocyte Glutathione Reductase Activation Coefficient, EGRAC
Erythrocyte Aspartate Aminotransferase Activation Coefficient, EAATAC
* National Diet and Nutrition Surveys of British Adults and the Elderly
Availability of Tests of Nutritional Status in the UK
The availability of tests may vary considerably across the country but most important nutrients can be assessed either at a local hospital or through a specialist laboratory. Details of specialist laboratories are given in the accompanying table.
Major NHS Nutritional Laboratories
| Location | Address |
| Birmingham | Regional Laboratory for Toxicology City Hospital Dudley Road Birmingham B18 7QH |
| Guildford | Trace Element Laboratory Centre for Clinical Science School of Biological Sciences University of Surrey Guildford GU2 5XH |
| London | Trace Metals Laboratory Department of Clinical Biochemistry King’s College Hospital Denmark Hill London SE25 9RS |
| London | Medical Toxicology Unit Avonley Road New Cross London SE14 5ER |
| Leeds | Department of Biochemistry Leeds General Infirmary Great George Street Leeds LS1 3EX |
| Liverpool | Department of Clinical Chemistry Royal Liverpool University Hospital Prescot Street Liverpool L7 8XP |
| Southampton | Trace Element Unit Clinical Biochemistry Department Southampton General Hospital Tremona Road Southampton SO16 6YD |
| Scotland – Glasgow | The Scottish Trace Element and Micronutrient Reference Laboratory Department of Clinical Biochemistry Glasgow Royal Infirmary Glasgow G4 0SF www.trace-elements.org.uk [An interesting website with useful information about laboratory assessment of nutrients] |
| Wales – Cardiff | Department of Medical Biochemistry and Immunology University Hospital of Wales Heath Park Cardiff CF14 4XW |
There are also private laboratories which also specialise in the assessment of essential nutrients see www.biolab.co.uk
