Measuring capillary blood ketones

Publication: 25/02/2018  
Next review: 29/10/2024  
Standard Operating Procedure
CURRENT 
ID: 5436 
Approved By: Trust Clinical Guidelines Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2021  

 

This Standard Operating Procedure is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.

Measuring capillary blood ketones

Adult clinical services at LTHT

Summary document

  1. Background
  2. Indications for measuring capillary blood ketones
  3. How to measure capillary blood ketones
  4. What to do if capillary blood ketone not immediately available?
  5. What to do if patient has a normal glucose (below 11 mmol/L) AND high ketone?
  6. What to do if patient has a high glucose (above 11 mmol/L) AND high ketone?
  7. Acting on the result of capillary blood ketone measurement in patients with diabetes AND hyperglycaemia
  8. Location in the trust of blood ketone meters

1. Background

Ketones (acetoacetate and b-hydroxybutyrate) are metabolic products resulting from increased use of body fat as an energy source.

Blood ketone levels become elevated in the following circumstances:

  1. Diabetic ketoacidosis, in which blood glucose is usually elevated  **
  2. Fasting can cause mild ketosis
  3. Prolonged starvation can cause ketotic hypoglycaemia
  4. Patients presenting after alcoholic excess, in the context of normal or low blood glucose
  5. Patients on a very low carbohydrate ketogenic diet

** Note diabetic ketoacidosis with normal or only slightly elevated blood glucose has been reported in some patients taking SGLT2 inhibitors (the ‘gliflozins), on insulin pumps (CSII) and can also occur in pregnancy .

The two main ketones are hydroxybutyrate and acetoacetate.
Capillary blood ketone testing measures blood hydroxybutyrate. This usually comes in an exact measureable numerical value in mmol/Litre.
Urine ketone testing measures acetoacetate and only gives a semi-quantitative result measured based on the urine ketone strips ranging from ‘+’ to ‘++++’

Hydroxybutyrate is the predominant ketone present in diabetic ketoacidosis and therefore this will be detected on capillary blood ketone testing. As diabetic ketoacidosis ( DKA) is treated, hydroxybutyrate is converted to acetoacetate. Hence, capillary blood ketones will fall but urine ketones will increase as acetoacetate increases. For this reason, blood ketone testing is a more reliable measure of the resolution of DKA.

EXCEPTIONS:

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2. Indications for measuring capillary blood ketones

Measure blood ketones in the following circumstances as stated by the LTH Capillary Blood Glucose Chart (Adults):

  1. Type 1 diabetes where patient has one capillary blood glucose above 14mmol/L, OR is clinically unwell.
  2. If patient does not have type 1 diabetes, but is treated with insulin AND is unwell with two consecutive capillary blood glucose readings above 14mmol/L .
  3. Patients on SGLT2 inhibitor (‘gliflozin’) who are hospitalised for major surgical procedures or have acute serious medical illnesses
  4. All patients with new hyperglycaemia > 11mmol/L ( not known to have diabetes)
  5. All patients with diabetes (of any type) and urine ketones 3+ or 4+ (to further quantify of the risk of DKA).
  6. Any patient with diabetes (of any type) with blood pH < 7.3 and/or serum bicarbonate < 15 mmol/L.
  7. Any patient without diabetes and blood pH < 7.3 and/or serum bicarbonate < 15 mmol/L where non-diabetic ketosis is suspected (discuss with Endocrinology).

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3. How to measure capillary blood ketones

The meter in use is Nova Biomedical StatStrip glucose/ketone (GLU/KET) monitoring system.  This is a glucose meter which has the additional function of ketone measurement enabled. These meters are networked and managed by Point of Care.
 
Only use these ketone-measurement-enabled capillary blood glucose meters to analyse blood ketones if you have been trained to do so. The meters will not allow ketone analysis to be performed by a user who has not had this specific training.  Training is provided by the company or by Point of Care to the ward and disseminated through key trainers.

Measure capillary blood ketones using a capillary blood sample as for measuring capillary blood glucose.

In the clinical notes and on the Capillary Blood Glucose Chart for Adults or Adult DKA treatment chart, record capillary blood ketone levels (units mmol/L).

Do NOT send sample to laboratory for ketone measurement.  Blood ketone measurement- enabled meters are available on the wards listed below. (See Item 8)

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4. What to do if capillary blood ketone not immediately available?

Urinary ketone measurements can be used to aid both clinicians and patients in making a decision, mainly to consider a diagnosis diabetes ketoacidosis. Where capillary blood ketones are not immediately available, measure urinary ketones to aid further clinical decision. Patients with urinary ketones 2+ or more with the clinical indications in Section 2 needs to be referred to the ward senior doctor initially for further review whilst waiting capillary ketone testing.
For the purpose of insulin correction guidance in hospital, we recommend against using urinary ketones to guide glucose correction.

Ketone Meter Equipment Funding Application
Each ward in LTHT is able to obtain and apply for a capillary ketone meter using the template business case which can be obtained from point of care team contact as below. The funding and application for capillary ketone meter would have to be agreed within the department / CSU. The completed business case must be supported and signed by a Lead Clinician and a Ward/Departmental Manager prior to consideration by the POCT Committee.
Further details (including business template can be obtained via email:

leedsth-tr.PointofCare@nhs.net

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5. What to do if patient has a normal glucose (below 11 mmol/L) AND high ketone?

Please seek senior and expert medical help.
Do NOT use subcutaneous insulin correction to correct high ketone due to risk of hypoglycaemia.

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6. What to do if patient has a high glucose (above 11 mmol/L) AND high ketone?

See further guidance and ketone flow chart (Appendix)

Important Note:

  1. The cut off use in this guidance for ketone measurement indication for patients known with diabetes is capillary blood glucose above 14 mmol/L. We acknowledge the difference where higher cut off glucose value (above 16mmol/L) for ketone measurement indication is used in the current nursing insulin plan and blood glucose monitoring form. This will be updated in the next planned review.

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7. Acting on the result of capillary blood ketone measurement in patients with diabetes AND hyperglycaemia

Guidance for action according to blood ketone (β-hydroxybutyrate) measurement:

blood ketone
(β-hydroxybutyrate)

Action

≤ 0.6 mmol/L

If the blood glucose level is elevated, manage appropriately.
Recheck blood glucose in 2 hours and if remains elevated check ketones.

>0.6 - 1.5 mmol/L

Inform medical team.
If the blood glucose level is elevated, consider giving additional ‘correction; rapid acting insulin (see guidance below).
Recheck blood glucose and ketones in 2 hours.
Ensure adequate fluid intake.

>1.5 - 3.0 mmol/L
HIGH RISK OF DKA

 

 

 

 

Inform medical team
Send a diabetes nurse referral

Treat raised blood glucose by giving additional “correction” rapid-acting insulin (see guidance below)

Ensure adequate fluid intake.
Retest blood glucose and ketones in 2 hours.

Consider and correct precipitating factors.
If patient is due for surgery that day then the surgeon should discuss with the anaesthetist.

Only consider variable rate IV insulin infusion (VRII) if correction with rapid acting insulin fails

> 3.0 mmol/L
HIGH
LIKELY DKA

Urgent medical assessment

Assess and manage diabetic ketoacidosis as per Adult DKA guideline. IV insulin Treatment guidelines if confirmed (acidotic pH <7.3 and/or bicarbonate < 15mmol/L, blood glucose>11mmol/L)
 
If patient does NOT have DKA, they are still likely to require additional insulin and fluid replacement.  Seek diabetes team support and give correction rapid acting insulin (see guidance below)

Recheck blood glucose and ketones hourly.

Consider and correct precipitating factors.
Patient is not safe for elective surgery or procedure.

*Please contact diabetes team for patients with elevated ketones on continuous subcutaneous insulin infusion (CSII) / ‘insulin pump’

Managing High Blood Glucose When Blood Ketone between 0.6 to 1.5mmol/L

Correction Insulin dose for moderate ketone levels

Blood Glucose level
(mmol/L)

Additional rapid acting insulin* dose
(see note below)

11 to 17 mmol/L

2 units

17.1 to 22 mmol/L

4 units

More than 22 mmol/L

6 units

Note:

  1. Additional insulin dose can be added as a ‘stat’ dose to patient’s usual insulin dose if this is already due.
  2. Do NOT give a correction dose of rapid acting insulin when
    (i) the patient is due rapid acting or premixed insulin in the next 3 hours
    or
    (ii) when the patient has had rapid acting or premixed insulin in the previous 3 hours.
  3. This can be repeated again in 2 hours if ketone still above range AND glucose above 11mmol/L AND usual insulin is not due
  4. If ketone rises above 1.5mmol/L, seek medical help and see next guidance on ‘Managing blood glucose when ketone above 1.5mmol/L

Managing High Blood Glucose When Blood Ketone above 1.5mmol/L

Correction Insulin dose for high ketone level

 

Ketone 1.5 to 3.0 mmol/L

Ketone above 3 mmol/L (with no evidence of DKA)

Total daily insulin dose (TTD)

Give an additional 10% of rapid acting insulin* every 2 hours

Give an additional 20% of rapid acting insulin* every 2 hours

Up to 14 units

1 unit

2 units

15 to 24 units

2 units

4 units

25 to 34 units

3 units

6 units

35 to 44 units

4 units

8 units

45 to 54 units

5 units

10 units

More than 54 units

10% of TTD

20% of TTD

 

Seek medical help if ketone levels not improving following second correction

Seek medical help if ketone levels are not improving following first correction

Adapted from Trend UK and DAFNE sick day rule guidance

*Suggested rapid acting insulin:
Novorapid, Humalog, Apidra, Fiasp, Trurapi, Lispro Sanofi (list not exhaustive)

We recommend not using Actrapid as the half-life is longer compared to the newer analogue insulin above. For the purpose of ketone correction in hospital setting, we recommend using Novorapid insulin. However, if patient have their own insulin listed above, this can also be used if available immediately in the ward.

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8.   Location in the trust of blood ketone meters

LGI

Jubilee

A&E

A&E Paeds

Rapid Assessment Unit

L02

L03

L04

L06

L07

L08

L15

Clarendon

Antenatal Day Care Clinic

L30

L37/CAT UNIT

L38

L40

L42

L45

Children's Clinical Research Facility

L47

L48

L52

Brotherton

NICPM

SJUH

Gledhow

Antenatal Day Unit (J-ADU)

J-03

J07

J07 Higher Observation Area

J08

J11

J-15

J-16

J-17

J19

J21

Chancellor

JAE

J-AMAA

J-26

J-27

J-29

Lincoln

David Beevers

J47

J48

Renal Intervention centre

J49

J50

Admission Lounge

J53/J54

Bexley

J81

Beckett

Manny Cussins

WGH

 

Diabetes

CAH

 

C2 Rheumatology

In addition of the location of blood ketones in the trust (this will expand in the future), Point of Care Team contact detail are provided below for support and information on up-to-date location list in the trust. Details are as below:

Ext Number: 22338
Email: leedsth-tr.pointofcare@nhs.net

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Appendix A: Ketone Flow Chart

Provenance

Record: 5436
Objective:
Clinical condition:
Target patient group:
Target professional group(s): Secondary Care Nurses
Adapted from:

Evidence base

Wrenn KD, Slovis CM, Minion GE, Rutkowski R. The syndrome of alcoholic ketoacidosis. The American journal of medicine. 1991 Aug 1;91(2):119-28.

Shah P, Isley WL. Ketoacidosis during a low-carbohydrate diet. New England journal of medicine. 2006 Jan 5;354(1):97-8.

Taylor SI, Blau JE, Rother KI. SGLT2 inhibitors may predispose to ketoacidosis. The Journal of Clinical Endocrinology & Metabolism. 2015 Aug 1;100(8):2849-52.

Cullen MT, Reece EA, Homko CJ, Sivan E. The changing presentations of diabetic ketoacidosis during pregnancy. American journal of perinatology. 1996 Oct;13(07):449-51.

Arora S, Henderson SO, Long T, Menchine M. Diagnostic accuracy of point-of-care testing for diabetic ketoacidosis at emergency-department triage. Diabetes care. 2011 Apr 1;34(4):852-4.

Approved By

Trust Clinical Guidelines Group

Document history

LHP version 2.0

Related information

Not supplied

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