Dynamic Tests

Report
CLINICAL
INVESTIGATION UNIT
TESTS
Presented by:
ALAA MONJED
Endocrinology fellow
OUTLINE
•
Background- Provocative endocrine tests
• CIU tests
 Indications
 Side effects / Contraindications
Background

What can we measure?
 basal hormone levels
 stimulated or suppressed hormone levels
 Why do we do dynamic endocrine testing?
 test of secretory reserve
 INSUFFICIENCY/DEFICIENCY
Stimulate!
 OVERPRODUCTION
Suppress!
Clinical Investigation Unit - CIU

Liz Froats, RN
 Room B5-502
http://dom.lhsc.on.ca/dom/divisions/endo/ciu.htm
http://lhdomws.lhsc.on.ca/dom/divisions/endo/ciu.htm
Available CIU Tests
Pituitary Hormonal Disorders
Tests
Acromegaly
Oral Glucose Tolerance test
GH deficiency
Insulin Tolerance test
Arginine/GHRH Stimulation test
Glucagon Stimulation test
Adrenal insufficiency
ACTH Stimulation test
Insulin Tolerance test
CRH Stimulation test
Central hypothyroidism
TRH Stimulation test
Hypogonadotropic Hypogonadism
GnRH Stimulation test
Anterior Pituitary insufficiency
(Double or Triple Bolus test)
Insulin Tolerance test
TRH Stimulation test
GnRH Stimulation test
Diabetes Insipidus
Water Deprivation test
Non-Pituitary Diseases
Tests
Medullary Thyroid
Cancer/Calcitonin
Calcium Stimulation test
Pentagastrin test
Hyperaldosteronism
Saline Infusion test
Pheochromocytoma
Plasma Catecholamines test
Hypoglycemia
8+ hour Fast test
Mixed Meal test
Examples
EVALUATION OF GROWTH
HORMONE DEFICIENCY
• Screening test: low IGF-1 level
• but normal IGF-1 does not exclude it
• Dynamic tests:
• because basal levels of GH are usually low, which
do not distinguish between normal and GHdeficient patients.
1. Insulin induced hypoglycemia
• Most reliable stimulus to GH secretion
• A subnormal increase in serumGH (<5.1 ng/mL) confirms
the diagnosis of growth hormone deficiency
ITT
14 units of insulin given
Time
Glucose (mmol/l) GH (ug/L)
0
3.96
1.77
15
1.2
0.98
30
0.8
3.24
60
2.3
3.26
90
1.3
2.83
120
2.1
0.95
• Interpretation:
• abnormal
• Why?
• Glucose fell to <2.2 mm
• Normally GH should rise over 10
2. GHRH-Arginine test
• 1mg GHRH combined with a 30-min infusion of
Arginine IV to stimulate GH secretion
• Possible side effects: mild flushing, metallic
taste, N/V
• Contraindications: severe liver or renal disease
3. Glucagon stimulation test
• 1 mg Glucagon IM, followed by measurement of
GH every 30 min for 3 hours
• Useful when ITT is contraindicated or GHRH is
not available
• Side effects: nausea, vomiting and possible late
hypoglycemia
• Contraindications: malnourished patients
• Failure of GH to rise > 3ng/ml is a positive test
Evaluation Of GH
Hypersecretion/Acromegaly
• Screening test: high IGF-1 level
• Dynamic tests:
• Oral glucose tolerance test
• Failure of GH suppression or paradoxical rise in GH
level confirms Acromegaly
• Also, seen in starvation, anorexia nervosa, and proteincalorie malnutrition
• Side effects: nausea
• If a radioimmunoassay method= GH level > 1mcg/L
• If one of the newer, highly sensitive
immunoradiometric GH assays is used= GH level > 0.3
mcg/L
Time
GLUCOSE (MM)
GH (ug/L)
0 min
4.7
19.7
30 min
11.0
15
60 min
7.5
12
90 min
5.3
10.8
120 min
3.1
14.9
Interpretation?
Evaluation Of LH/FSH
Deficiency
1. Measurement of gonadal steroids (estradiol,
testosterone).
2. Measurement of LH/FSH.
• Primary gonadal failure
• Low gonadal steroids, High LH/FSH
• Hypogonadotrophic hypogonadism
• Low gonadal steroids, LH,FSH
3. GnRH test
• Assess LH/FSH secretory reserve by stimulating their secretion
• Uncommonly performed
Evaluation Of
TSH(Secondary
Hypothyroidism)
1. Measurement of TSH
2. Measurement of free T4/free T3
• If high TSH, low T4 …….
• If low/normal TSH, low T4 …….
3. TRH stimulation test
• is rarely done now because of the accurate
methods of determining TSH and freeT4
EVALUATION OF
HYPOPITUITARISM
•
Components:
• Insulin Tolerance Test
• GH deficiency, adrenal insufficiency
• GnRH stimulation test
• hypogonadotropic hypogonadism
• TRH stimulation test
• central hypothyroidism, hypoprolactinemia
1984. J Neurosurg 61(3):586-590
ACTH and Cortisol Secretion
Kronenberg HM et al. Williams Textbook of Endocrinology. 11th edition. 2008 Saunders Elsevier.
ACTH and Cortisol Secretion
24:00
08:00
12:00
20:00
 pulsatile secretion
 circadian rhythm
 highest in a.m.
Kronenberg HM et al. Williams Textbook of Endocrinology. 11th edition. 2008 Saunders Elsevier.
Pituitary-Adrenal Reserve
Dynamic Tests
• Used to evaluate the ability of the HPA axis to
respond to stress
1.
ACTH stimulation test: directly stimulates adrenal secretion
2.
Metyrapone test: inhibits cortisol synthesis and stimulates
pituitary ACTH secretion
3.
Insulin-induced hypoglycemia: stimulates ACTH secretion by
increasing CRH
4.
CRH test: stimulates directly the pituitary corticotrophs to
release ACTH
Adrenal Insufficiency Diagnosis
Steps:
1. To rule out adrenal insufficiency - fasting 08:00 am
cortisol
 if 08:00 am cortisol >524 nmol/L, adrenal
insufficiency excluded
 if 08:00 am cortisol <83 nmol/L, adrenal
insufficiency confirmed
 if 08:00 am cortisol between these values, is
borderline – need further testing
reviewed in Oelkers W. N Engl J Med 1996; 335(16):1206-1212
Adrenal Insufficiency Diagnosis
Steps:
2. If suspect primary adrenal insufficiency, do both 08:00
am cortisol and ACTH
 low cortisol and high ACTH - primary
•
if cortisol normal – rules out primary, but does not
exclude mild secondary adrenal insufficiency
•
in primary adrenal insufficiency – ACTH usually >22pmol/L
 low cortisol and low/normal ACTH –
secondary/tertiary
Adrenal Insufficiency Diagnosis
• Dynamic Tests:
 To confirm adrenal insufficiency:
 High dose ACTH stimulation test
 Fasting is not required
 250 mg cosyntropin (Cortrosyn) IV/IM
 Cortisol/ACTH at -15, 0, 30, 60 min
 If peak cortisol >500 nmol/L (preferably >550 nmol/L),
rules out primary adrenal insufficiency
Oelkers W. N Engl J Med 1996; 335(16):1206-1212
• A normal response to ACTH stimulation test:
• Excludes primary AI
• Excludes overt secondary AI with adrenal atrophy
• Dose not rule out partial ACTH deficiency
• pts with sufficient basal ACTH secretion to prevent
adrenocortical atrophy
• Or pts with recently developed secondary AI who have not yet
undergone adrenal atrophy
• In such patients, other pituitary-adrenal reserve
dynamic testing may be indicated
Adrenal Insufficiency Diagnosis
• Low dose short ACTH stimulation test
• must be undertaken in the morning
• 1 mg cosyntropin (Cortrosyn) IV
•
Cortisol/ACTH at -15, 0, 30, 60 min
• Normal peak cortisol >500 nmol/L
• 2 meta-analyses comparing low vs. high dose tests
had conflicting results:
• Dorin et al. 2003 – no difference in sensitivity or specificity
• Kazlauskaite et al. 2008 – low dose test had higher
sensitivity
Oelkers W. N Engl J Med 1996; 335(16):1206-1212
Adrenal Insufficiency Diagnosis
• Insulin-induced hypoglycemia test:
• It measures the integrity of the HPA axis and its ability
to respond to stress
• Normal plasma cortisol response: an increment
>220nmol/l and a peak level >550 nmol/l
• Normal ACTH response > 22pmol/l
• A normal response exclude AI and decreased pituitary
reserve i.e. no need to cortisol therapy during illness or
stress
• Contraindicated in: Elderly, CVD, CVA and seizure
disorders
Adrenal Insufficiency Diagnosis
 To distinguish secondary vs. tertiary adrenal
insufficiency: CRH stimulation test (if you can get
CRH!)
 100 mg CRH IV
 ACTH, cortisol at -15, 0, 30, 60, 90 min
 low/absent ACTH = pituitary adrenal
insufficiency (secondary)
 high ACTH = hypothalamic adrenal insufficiency
(tertiary)
(values not as well standardized as for ITT)
Oelkers W. N Engl J Med 1996; 335(16):1206-1212
Posterior Pituitary
Diabetes Insipidus
• Central
• Antidiuretic hormone deficiency
• Responds to Desmopressin
• Diagnosis:
• Water Restriction Test
Water Restriction Test
Water Deprivation Test
TIme
Weight (kg)
Urine osmol
Serum osmol Serum Na
0800
82.6
150
290
144
0900
82.4
160
1000
82.1
200
295
148
1100
81.9
210
1200
81.6
225
300
149
1300
81.5
211
312
150
1400
81.1
231
298
145
1500 **
487
• Interpretation: abnormal, consistent with central DI
• Why?
• Serum osmolality rose but urine osmolality
remained relatively dilute still; similarly serum Na
rose
• [At ** time DDAVP was given and
serum/urine/Na responded appropriately]
REFRENCES
 Kronenberg HM et al. Williams Textbook of
Endocrinology. 11th edition. 2008 Saunders Elsevier.
 Gardner DG & Shoback D (eds) Greenspan’s
Basic & Clinical Endocrinology, 9th Edition. 2011
McGraw-Hill.
 www.uptodate.com
 http://dom.lhsc.on.ca/dom/divisions/endo/ciu.ht
m
THANK YOU

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