Transcript Slide 1

BNP | Haemochromatosis | Vitamin D
Testing in
Primary Care
1. BNP
2. Haemochromatosis
3. Vitamin D
BNP
Key recommendations:
•
BNP is useful as a ‘rule-out’ test of heart failure in acute
dyspnoea
•
The use of BNP in primary care is not yet established
BNP 1
Introduction
BNP assays have an important role in the exclusion
of heart failure.
• Normal levels virtually exclude the diagnosis of
heart failure
• High levels effectively confirm the diagnosis
• Intermediate levels require confirmation by
echocardiography
BNP 2
Underlying pathophysiology
BNP:
• secreted in response to ventricular distension
• helps regulate salt and water excretion
• helps maintain blood pressure
• NT-proBNP and BNP results are not comparable
BNP 3
Underlying pathophysiology
BNP 4
BNP is useful as a ‘rule-out’ test of heart
failure when a patient presents with acute
dyspnoea and the diagnosis is not clear
• In patients with dyspnoea BNP levels have good
sensitivity for heart failure
• BNP has low specificity – it can be elevated by other
conditions such as acute PE or cor pulmonale
BNP 5
Interpretation of BNP results in
acute dyspnoea
It is important to interpret the
result using the ranges
provided by the testing
laboratory. Laboratory
ranges for low,
indeterminate and high
results vary between
laboratories and the
particular assay used.
BNP 6
The use of BNP in primary care is not yet
established
•
BNP and ECG are equally effective for initial workup
•
BNP’s role in identifying patients with asymptomatic
ventricular dysfunction not yet determined
•
No clear role for those already on therapy
•
Inconclusive evidence for use in primary care
BNP 7
Haemochromatosis
gene testing
Key recommendations:
• Transferrin saturation and ferritin are used for diagnosis
• Population screening is not recommended
• First degree adult relatives of patients should be tested
• People with haemochromatosis should be monitored
with transferrin saturation and ferritin
Haemochromatosis 1
Defining haemochromatosis
• Approximately 1 in 7 people are carriers
• One in 200 are homozygous
• Occurs in people of Nordic or Celtic ancestry
Haemochromatosis 2
Haemochromatosis
Causes increased iron absorption:
• ↑ transferrin saturation
• ↑ iron accumulation
• ↑ ferritin
• Iron deposition may cause organ damage
Haemochromatosis 3
Haemochromatosis Gene
• C282Y mutation on the HFE gene
• 90% of people with clinical features are homozygous
• Other HFE gene mutations have now been recognised
Haemochromatosis 4
Symptoms of
haemochromatosis
• Fatigue, weakness, arthralgias, impotence, weight
loss, abdominal pain and hyperpigmented skin
• Symptoms are often vague and nonspecific
• A poor indicator of disease
Haemochromatosis 5
Serum transferrin saturation
and ferritin are the best initial
tests
• ↑ transferrin saturation is usually the first change
• Ferritin levels rise as iron stores accumulate, but
is non-specific
• 50% transferrin saturation warrants HFE gene
testing
Haemochromatosis 6
Population screening
of asymptomatic individuals for haemochromatosis
is currently not recommended
• Haemochromatosis has been suggested for
population screening
• Has not been widely supported
• Doubts about the cost-effectiveness of a screening
programme
Haemochromatosis 7
Test first degree adult
family members
• Screen using transferrin saturation, ferritin and HFE
gene testing
• Testing in children can be delayed until > 20 years old
• Partner can be tested to assess their carrier status,
which can help determine the child’s risk
• Counseling should be included in the process
Haemochromatosis 8
Testing for haemochromatosis
When
haemochromatosis
is suspected, tests
should be
requested in a
cascade manner,
with each result
suggesting the path
of further testing.
Haemochromatosis 9
Monitoring
haemochromatosis
• Test transferrin saturation and ferritin at least 1-2 yearly
• Therapeutic phlebotomy is indicated when the ferritin is
consistently elevated
• Target ferritin is < 50 ug/L
• Gene should only performed one occasion
Haemochromatosis 10
Vitamin D testing
Key recommendations:
•
Increased sun exposure is advisable for people
at high risk of vitamin D insufficiency due to
inadequate exposure
•
Vitamin D and calcium supplementation is
appropriate for people at high risk who cannot
increase their sun exposure
Vitamin D 1
Vitamin D testing
Key recommendations – continued:
•
Routine testing of vitamin D levels is not usually
necessary prior to or after starting vitamin D
supplementation
•
Vitamin D testing is appropriate for people in
specific situations
Vitamin D 2
Introduction
•
Rickets and osteomalacia are rare
•
Increasing concern of vitamin D levels in some
people
•
 vitamin D levels more common in older people
•
International interest in vitamin D
supplementation for older people
Vitamin D 3
Pathophysiology
There are two main forms of vitamin D:
• Vitamin D3 (cholecalciferol): produced in the skin by
the action of UV light
• Vitamin D2 (ergocalciferol) produced by plants
• Most vitamin D is produced as a result of exposure
to sunlight
• Food provides ~ 10% of vitamin D
Vitamin D 4
Recommended
sun exposure
• Daily exposure ~ 15% of body surface to 1/3 MED will
provide sufficient vitamin D
• Older people and dark skinned people require more
exposure
• Avoid deliberate exposure between 10:00 and 14:00
• Glass blocks vitamin D production
Vitamin D 5
Recommended
sun exposure
Dec Jan
July - Aug
Region
At 10:00
or 14:00
At 10:00 or
14:00
At 12:00
Minutes
Auckland
6–8
Minutes
30 – 47
Minutes
24
Minutes
Christchurch
6–9
Minutes
49 – 97
Minutes
40
Minutes
Vitamin D 6
People at risk of low
vitamin D levels
•
Older people in residential care
•
Older people admitted to hospital
•
Patients with hip fracture
•
Dark-skinned men and women (particularly if veiled)
•
Mothers of infants with rickets
•
People unable to obtain regular sun exposure
Vitamin D 7
Supplementing with
cholecalciferol
Supplementation may be given without testing for
asymptomatic people at risk of low vitamin D
because it is safe and relatively inexpensive,
whereas testing is expensive
Vitamin D 8
Supplementing with
cholecalciferol
• Supplementation reduces the risks of fractures in
the elderly, particularly those in institutions
• Supplementation must be combined with an
adequate calcium intake
• the evidence is conflicting for other groups at risk of
vitamin D deficiency
Vitamin D 9
Cholecalciferol Dose
• An appropriate dose is a single tablet of cholecalciferol
1.25 mg (50,000 IU) monthly by mouth
• This dose is effective and not associated with risk of
toxicity
• For effective supplementation adequate calcium intake
is required (1.5 g daily). This may require calcium
supplementation
Vitamin D 10
Consider supplementation
rather than testing
• Vitamin D testing is expensive
• Likely to be positive in people at high risk.
• Reasonable to supplement asymptomatic at risk
people without testing
Vitamin D 11
When should I test for vitamin D
• Unexplained raised serum alkaline phosphatase or
low calcium or phosphate
• Atypical osteoporosis
• Unexplained proximal limb pain in older people
• Unexplained bone pain, unusual fractures or other
evidence suggesting metabolic bone disease.
(Consider specialist advice for people in this category)
Vitamin D 12