Table 11, Protocol for laboratory monitoring of nutrition support - Nutrition Support for Adults

Parameter	Frequency	Rationale	Interpretation
Sodium, potassium, urea, creatinine	Baseline Daily until stable Then 1 or 2 times a week	Assessment of renal function, fluid status, and Na and K status	Interpret with knowledge of fluid balance and medication Urinary sodium may be helpful in complex cases with gastrointestinal fluid loss
Glucose	Baseline 1 or 2 times a day (or more if needed) until stable Then weekly	Glucose intolerance is common	Good glycaemic control is necessary
Magnesium, phosphate	Baseline Daily if risk of refeeding syndrome Three times a week until stable Then weekly	Depletion is common and under recognised	Low concentrations indicate poor status
Liver function tests including International Normalised Ratio (INR)	Baseline Twice weekly until stable Then weekly	Abnormalities common during parenteral nutrition	Complex. May be due to sepsis, other disease or nutritional intake
Calcium, albumin	Baseline Then weekly	Hypocalcaemia or hypercalcaemia may occur	Correct measured serum calcium concentration for albumin Hypocalcaemia may be secondary to Mg deficiency Low albumin reflects disease not protein status
C-reactive protein	Baseline Then 2 or 3 times a week until stable	Assists interpretation of protein, trace element and vitamin results	To assess the presence of an acute phase reaction (APR). The trend of results is important
Zinc, copper	Baseline Then every 2–4 weeks, depending on results	Deficiency common, especially when increased losses	People most at risk when anabolic APR causes Zn ↓ and Cu ↑
Selenium^a	Baseline if risk of depletion Further testing dependent on baseline	Se deficiency likely in severe illness and sepsis, or long-term nutrition support	APR causes Se ↓ Long-term status better assessed by glutathione peroxidase
Full blood count and MCV	Baseline 1 or 2 times a week until stable Then weekly	Anaemia due to iron or folate deficiency is common	Effects of sepsis may be important
Iron, ferritin	Baseline Then every 3–6 months	Iron deficiency common in long-term parenteral nutrition	Iron status difficult if APR (Fe ↓, ferritin ↑)
Folate, B12	Baseline Then every 2–4 weeks	Iron deficiency is common	Serum folate/B12 sufficient, with full blood count
Manganese^b	Every 3–6 months if on home parenteral nutrition	Excess provision to be avoided, more likely if liver disease	Red blood cell or whole blood better measure of excess than plasma
25-OH Vit D^b	6 monthly if on long-term support	Low if housebound	Requires normal kidney function for effect
Bone densitometry^b	On starting home parenteral nutrition Then every 2 years	Metabolic bone disease diagnosis	Together with lab tests for metabolic bone disease

Parameter

Frequency

Rationale

Interpretation

Sodium, potassium, urea, creatinine

Baseline

Daily until stable
Then 1 or 2 times a week

Assessment of renal function, fluid status, and Na and K status

Interpret with knowledge of fluid balance and medication

Urinary sodium may be helpful in complex cases with gastrointestinal fluid loss

Glucose

Baseline

1 or 2 times a day (or more if needed) until stable

Then weekly

Glucose intolerance is common

Good glycaemic control is necessary

Magnesium, phosphate

Baseline
Daily if risk of refeeding syndrome
Three times a week until stable
Then weekly

Depletion is common and under recognised

Low concentrations indicate poor status

Liver function tests including International Normalised Ratio (INR)

Baseline

Twice weekly until stable

Then weekly

Abnormalities common during parenteral nutrition

Complex. May be due to sepsis, other disease or nutritional intake

Calcium, albumin

Baseline

Then weekly

Hypocalcaemia or hypercalcaemia may occur

Correct measured serum calcium concentration for albumin

Hypocalcaemia may be secondary to Mg deficiency

Low albumin reflects disease not protein status

C-reactive protein

Baseline

Then 2 or 3 times a week until stable

Assists interpretation of protein, trace element and vitamin results

To assess the presence of an acute phase reaction (APR).
The trend of results is important

Zinc, copper

Baseline

Then every 2–4 weeks, depending on results

Deficiency common, especially when increased losses

People most at risk when anabolic

APR causes Zn ↓ and

Cu ↑

Selenium^a

Baseline if risk of depletion

Further testing dependent on baseline

Se deficiency likely in severe illness and sepsis, or long-term nutrition support

APR causes Se ↓

Long-term status better assessed by glutathione peroxidase

Full blood count and MCV

Baseline

1 or 2 times a week until stable

Then weekly

Anaemia due to iron or folate deficiency is common

Effects of sepsis may be important

Iron, ferritin

Baseline

Then every 3–6 months

Iron deficiency common in long-term parenteral nutrition

Iron status difficult if APR (Fe ↓, ferritin ↑)

Folate, B12

Baseline

Then every 2–4 weeks

Iron deficiency is common

Serum folate/B12 sufficient, with full blood count

Manganese^b

Every 3–6 months if on home parenteral nutrition

Excess provision to be avoided, more likely if liver disease

Red blood cell or whole blood better measure of excess than plasma

25-OH Vit D^b

6 monthly if on long-term support

Low if housebound

Requires normal kidney function for effect

Bone densitometry^b

On starting home parenteral nutrition

Then every 2 years

Metabolic bone disease diagnosis

Together with lab tests for metabolic bone disease

From: 7, Monitoring of nutrition support in hospital and the community

Nutrition Support for Adults: Oral Nutrition Support, Enteral Tube Feeding and Parenteral Nutrition.

NICE Clinical Guidelines, No. 32.

National Collaborating Centre for Acute Care (UK).

London: National Collaborating Centre for Acute Care (UK); 2006 Feb.

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Table 11Protocol for laboratory monitoring of nutrition support