Download Dynamic Function Tests and Protocol

Dynamic function tests and protocols
All endocrine dynamic function testing should be performed
under medical supervision, by appropriately qualified staff with
experience of performing the tests being undertaken.
Last updated 21/04/2011
Name
Protocol
24hr urine collection protocol
Creatinine clearance protocol
Oral Glucose Tolerance test (OGTT)
Gestational OGTT
See below
See below
See below
See below
Synacthen test
Adults
See below
Paediatric protocol
Contact SHSCT Endocrinologists
Diabetes Insipidus investigation
(water deprivation test)
Cortisol Diurnal
Investigation of
Rhythm
Cushing syndrome
24hr urine
cortisol
See below
Contact Regional Endocrine Laboratory
028 90 633798
Dexamethone
Contact SHSCT Endocrinologists
suppression test.
Investigation of insulinoma
Contact SHSCT Endocrinologists
Investigation of
Urine
Contact Regional Endocrine Laboratory
Phaeochromocytoma Catacholamines 028 90 633798
Forearm Non-ischaemic Exercise Test
Pituitary Function Test (Combined)
Paediatric Endocrine Test Protocols
http://www.metbio.net/docs/MetBioGuideline-KEGA290980-21-03-2010.pdf
Contact Regional Endocrine Laboratory
028 90 633798
Paediatric Endocrinologist
02890 633598
Local Guidelines
Disturbance
Hyponatraemia
Guidelines location
Hyponatraemia guidance
http://shsctintranet.hpss.ni.nhs.uk/HTML/documents/hyponatraemia
.pdf
Calculated example
Click Here
Crest Guidelines
Click Here
Crest wall chart
Click Here
Hyperkalaemia
Click Here
Hypokalaemia
Hypophosphataemia
Click Here
Click Here
Hypomagnesaemia
Click Here
Hypocalcaemia
Hypercalcaemia
See BNF Guidance
See BNF Guidance
Oral Glucose Tolerance test (OGTT) protocol
(a) ADULT ORAL GLUCOSE TOLERANCE TEST
Indication
Used for diagnosis when blood glucose levels are equivocal.
Technique
After at least 3 days of unrestricted diet (>150g of carbohydrate daily) and
usual physical activity. Test should be preceded by an overnight fast of 8 -14
hrs, during which water may be drunk.
Smoking not permitted during test.
Collect fasting blood sample
Patient should drink 75g of anhydrous glucose or 82.5g of glucose
monohydrate in 250 - 300 ml of water over 5 minutes.
Collect 2 hr blood sample.
Values for diagnosis of diabetes mellitus and other categories of
hyperglycaemia according to the WHO.
Serum/plasma glucose (mmol/L)
DIABETES MELLITUS
Fasting or
2hrs after glucose load
 7.0
11.1
IMPAIRED GLUCOSE TOLERANCE (IGT)
Fasting and
< 7.0
2hrs after glucose load
 7.8 - < 11.1
IMPAIRED FASTING GLYCAEMIA (IFG)
Fasting and
2hrs after glucose load
 6.1 - < 7.0
< 7.8
(b) ORAL GLUCOSE TOLERANCE TEST IN PREGNANCY
Indication
Used for diagnosis when blood glucose levels are equivocal.
Technique
After at least 3 days of unrestricted diet (>150g of carbohydrate daily) and
usual physical activity. Test should be preceded by an overnight fast of 8 -14
hrs, during which water may be drunk.
Smoking not permitted during test.
Collect fasting blood sample
Patient should drink 75g of anhydrous glucose or 82.5g of glucose
monohydrate in 250 - 300 ml of water over 5 minutes.
Collect.1 & 2 hr blood sample
Values for the diagnosis of gestational diabetes mellitus according to
International Association of Diabetes and pregnancy Study Groups
Consensus panel
Fasting plasma glucose
5.1 mmo/L
1hr plasma glucose
10.0mmo/L
2 hr plasma glucose
8.5 mmo/L
Investigation of suspected adrenal insufficiency
(A) 09:00 AM CORTISOL
A 08:00–09:00 cortisol value of Intact adrenocortical reserve can usually be
confirmed with basal morning cortisol concentrations of .500 nmol/L. The
exclusion of adrenal insufficiency for those with intermediate serum cortisol
concentrations (100–500 nmol/L) often requires further dynamic testing.
Note basal morning cortisol value are variable and may be affected by
stress, exercise and food intake. it is advisable to discontinue oestrogen
therapy for a period of at least six weeks prior to assessing the HPA axis.
Low serum albumin concentrations, as found in hypoproteinaemic states such
as hepatic or renal failure, may lead to misleadingly reduced total serum
cortisol concentrations despite normal biologically active free cortisol
concentrations
(B) Short Synacthen test for suspected adrenal failure
Indication
This is performed for the investigation of adrenal insufficiency and the
diagnosis of congenital adrenal hyperplasia. There is no evidence to support
the use of this test in the management of steroid replacement or withdrawal.
Principle
Adrenal glucocorticoid secretion is controlled by adrenocorticotrophic
hormone (ACTH) released by the anterior pituitary. This test evaluates the
ability of the adrenal cortex to produce cortisol after stimulation by synthetic
ACTH (tetracosactide; Synacthen ®). It does not test the whole pituitaryadrenal axis.
Side effects
There are rare reports of hypersensitivity reactions to ‘Synacthen’ particularly
in children with history of allergic disorders.
Preparation
There are no dietary restrictions for this test. This test should be ideally
performed in the morning but may be done at any time of the day. If there is
an inadequate response in the afternoon refer to endocrinology and consider
repeating the test in the morning.
Requirements
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2 clotted gel tubes
250 microgram Synacthen (1 vial)
the dose for children is 36 microgram/kg body weight up to a maximum
of 250 micrograms
Procedure
09:00h
take 3 mL blood for cortisol
inject Synacthen iv or im
09:30h take further sample for cortisol
Interpretation
1. Adrenal insufficiency is excluded by a 30 min value > 550 nmol/L
(Roche method). The incremental rise or 60 minute value does not
provide additional useful information.
2. An abnormal result should prompt referral to an endocrinologist.
3. Interpretation of basal and stimulated cortisol in the ICU setting is
controversial.
4. If the patient is taking steroids discuss with the laboratory or an
endocrinologist before the synacthen test is performed.
5. In ACTH deficiency the response to the short test may be normal or
reduced. Care should be taken when interpreting synacthen tests in
pituitary disease.
6. Baseline and incremental cortisol values do NOT apply to women
taking oral contraceptives or to pregnant women. Omit oestrogen
replacement for 6 weeks prior to the test (as increased CBG will make
cortisol results difficult to interpret) and discuss with an endocrinologist.
Cortisol Diurnal Rhythm
Indications The investigation of patients with suspected Cushing's
Syndrome.
Preparation
The patient should not be taking steroids or ACTH.
The contraceptive pill can also produce an increase in cortisol.
Minimise undue distress to the patient due to Repeated venepuncture, the
procedure of admission and other factors which may render accurate
interpretation more difficult.
Procedure
09.00 hours: Take 2 mL blood (plain tube) for serum cortisol.
20.00 hours: Take 2 mL blood for serum cortisol.
Reference ranges
7-10am 171-536nmol/L
4-8pm
64-327nmol/L
Estimation of Creatinine Clearance as a Guide to Glomerular Filtration Rate
Introduction
Creatinine is a by-product of muscular metabolism. It is filtered at the
glomerulae and excreted in the urine without further reabsorption or excretion
by the tubules. For this reason, it is a valuable monitoring analyte for
glomeruli filtration rate. This is of value in the diagnosis and monitoring of
renal disease.
Note: An estimated GFR result is now reported on all electrolyte profiles. It is
calculated from the serum creatinine and patients’ age and reported as part of
the electrolyte profile. A 24hr urine collection for GFR is not now normally
required for adults.
Creatinine clearance
Creatinine clearance is defined as the volume of blood in mls containing the
amount of creatinine which appears in the glomerular filtrate produced in one
minute. The classical formula is:UxV
P
Where U = Urinary creatinine in micromol / litre
V = Volume of urine produced in 1 minute (24 hr volume / 1440)
P = Serum creatinine in micromol / litre
Creatinine Clearance gives results comparable to inulin clearance
Sample requirements
An accurately timed 24 hr urine taken into thymol is required although an
acidified 24 hr urine specimen is also acceptable. A clotted blood sample for
serum creatinine should be taken at some time during the 24hr urine
collection.
For unusually large or small patients, the clearance rate obtained is referred
to the mean body surface area (BSA) of 1.73 m2. The BSA can be
determined from nomograms for height and weight hence:Corrected creatinine clearance = 1.73 x calculated creatinine clearance/
surface area in m2
Under-estimation of creatinine clearance can occur with increased tubular
creatinine reabsorption, such as exists in congestive cardiac failure; while
over-estimation occurs in advanced renal failure, due to increased tubular
excretion of creatinine.
Reference Ranges
70 – 150 mls/minute
24hr collection protocol
Introduction
The accuracy and usefulness of investigations which require a timed
collection of urine depends largely on obtaining a full and complete collection.
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The bladder should be emptied at the start of the collection
(conveniently 8 am) whether or not the patient feels the need and this
urine discarded.
Note the start time (i.e. exact time the bladder was emptied) on the
bottle label.
Collect all urine passed for the next 24 hours.
Exactly 24 hours later the bladder should be emptied completely,
whether or not the patient feels the need. Add this final specimen to
complete the 24hr collection.
Screw the lid on securely.
Note the End time (i.e. when bladder emptied) on the bottle label.
Send the completed collection and request form with the times and
date clearly noted to the laboratory without delay.