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Rational Request of Endocrine tests

Rational Request of Endocrine tests. دکتر کوروش هاشمی اصل MD,MPH. The Test. Measuring an analytic as a Marker to distinguish health and disease Ideal Marker Absolutely specific for a specific disease Easily measurable Quantity reflective of severity of disease

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Rational Request of Endocrine tests

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  1. Rational Request of Endocrine tests دکتر کوروش هاشمی اصل MD,MPH

  2. The Test Measuring an analytic as a Marker to distinguish health and disease Ideal Marker • Absolutely specific for a specific disease • Easily measurable • Quantity reflective of severity of disease • Early detection following onset of disease • Not affected by other biological disturbances Highly Specific marker: TroponinI. It is a marker of Myocardial infarction (Heart Attack) Found predominately in Cardiac Tissue Released into the blood stream following cell death Non specific marker: low blood pH (acidosis) Very important to know but can be caused by a hosts of events Drugs Respiratory problems Renal problems

  3. Sensitivity: The ability to detect people who do have disease • Specificity: The ability to detect people who do not have disease • Positive Predictive Value: The likelihood that a person with a positive test result actually has disease • Negative Predictive Value: The likelihood that a person with a negative test result truly does not have disease

  4. Sensitivity“Be sensitive to those who have disease” True Positive(A) True Positive(A)+ False Negative(C)

  5. Specificity“Negative people get specific” True Negative (D) True Negative(D)+ False Positive(B)

  6. Positive Predictive Value True Positive True Positive+ False Positive

  7. Negative Predictive Value True Negative True Negative+ False Negative

  8. Likelihood Ratios: What do they mean? LR+ = sensitivity / (1-specificity) LR- = (1-sensitivity) / specificity LR>10 strong evidence to R/I a disease LR<0.1 strong evidence to R/O a disease

  9. Examples of Common Diseases, Tests, and Likelihood Ratios

  10. Thyroid test • FNA حساسیت و ویژگی بالائی دارد از سویی اگر FNA مثبت شدLR+=4.5 است و اگر منفی شد LR-=0.12 • بنابراین FNA تست مناسبی برای نودل تیروئید در موارد TSH نرمال می باشد. • FNA+ = بدخیمی در حد بالای 20% • FNA- = بدخیمی در حد کمتر از 5% • ندول بزرگ (>4 سانت) - رشد سریع اخیر - آدنوپاتی

  11. Diagnostic testing Diagnostic test Posttest probability Pretest probability Disease prevalence Sensitivity, specificity PPV, NPV

  12. TEST CHARACTERISTICS TEST CHARACTERISTICS RELIABILITY VALIDITY Validityاشاره به مناسب بودن یا معناداری اندازه گیری دارد Individuality Index Reliabilityبه ثبات یا پایایی اندازه گیری اشاره دارد Sen,sp,ppv,npv

  13. Reliability میزان تست کمتر از 10% یعنی در صورت تکرار تست کمتر از 10% نسبت به عدد قبلی تغییر می کند(تست خوبی است)

  14. Individuality Index Index of individuality= اندکس فردیت = CVw CVb تغییرات یک تست در خود فرد تغییرات تست در بین افراد(رنج نرمال)

  15. Individuality Index

  16. Individuality Index سناریو: خانم 40 ساله با T4=11.5 ( بازه نرمال= 4.5 – 12) مراجعه کرده است . • آیا وی هیپرتیروئید است؟ • چه آزمایش دیگری لازم است؟

  17. Why are laboratory tests ordered • Diagnosis • Monitor progression of disease • Monitor effectiveness of treatment • Screening population for diseases • To identify complications of treatment • For predicting survivability, employability • To conduct research • To prevent malpractice • For educating residents • To assess nutritionalstatus and health of an health individual

  18. PSEUDO-DISEASE • Over – diagnosis insidentaloma • Competing risk prostatic Ca in elderly • Serendipity Adrenal tumor in CT • Fals-positive Thyroid nodule

  19. Multiple Testing • Check up 1 test = 5% 6 tests = 24% 12tests= 43% Ulysses syndrome = extensive diagnostic investigation

  20. Thyroid test • تشخیص اولیه • هیپو تیروئیدی اولیه: TSH – T4 یا TSH • هیپرتیروئید: TSH –T4 – T3 یا FT4-FT3-TSH • پیگیری بیمار • هیپوتیروئیدی و گواتر : TSH • هیپرتیروئیدی: T3 –T4 و در فاز های بعدی TSH • اندیکاسیون T3 : • در هیپوتیروئیدی جائی ندارد • درهیپرتیروئیدی ، در صورت پائین بودن TSH درموارد زیر کمک کننده است: • FT4 نرمال • هیپرتیروئیدی ناشی از آمیدارون • بررسی و پیش بینی عود در گریوز

  21. رابطه T4 با TSH یک رابطه لگاریتمی است و تغییرات کم T4 اثر زیادی بر TSH خواهد داشت.در نتیجه در بیماری که تحت درمان با لووتیروکسین است و T4 بالا و TSH نرمال دارد نیازی به افزایش دوز دارو نیست.

  22. Endocinologic Diagnostic test ADRENAL PROBLEMS • Addisons Disease:, plasma ACTH, renin, aldosterone, adrenal antibodies. • ACTH Deficiency (as in hypopituitarism): plasma cortisol CALCIUM PROBLEMS • Hypocalcaemia: Plasma parathyroid hormone, 25(OH)-vitamin D, ionised calcium, fasting urine calcium:creatinine ratio. • Hypercalcaemia: Parathyroid hormone, (if normal, PTH related peptide, 25(OH)-vitamin D).

  23. Endocinologic Diagnostic test GONADAL PROBLEMS (FEMALE) • Amenorrhoea/Menstrual Disturbance: LH, FSH, prolactin, oestradiol. If prolactin raised, TSH and free thyroxine index. Tests for hirsutism if indicated. • Menopause: Raised LH & FSH, low oestradiol may indicate that the patient is perimenopausal. Considerable fluctuations may be seen over many months until the patient is truly menopausal. Patients receiving HRT will usually show a fall in LH and FSH, but symptoms and bone density are probably better parameters to monitor. • Hirsutism:Basic screening: plasma testosterone, sex hormone binding globulin. Additional tests: LH, FSH, adrenal androgens (e.g. DHEAS), 17-OH progesterone. Tests for Cushing's and acromegaly if indicated

  24. Endocinologic Diagnostic test GLUCOSE (ISLET CELL) PROBLEMS • Hypoglycaemia: Plasma insulin (after overnight fast or during hypoglycaemic episode), measure glucose on same sample as insulin. C-peptide measurement will distinguish between endogenous and exogenous sources of insulin. Sulphonylurea assay if raised insulin and C-peptide in presence of hypoglyaemia.

  25. Endocinologic Diagnostic test GONADAL PROBLEMS (MALE) • Gynaecomastia: Plasma oestradiol, LH, FSH, prolactin, testosterone, sex hormone binding globulin, betaHCG, alpha-foetoprotein. • Impotence: Testosterone, sex hormone binding globulin, prolactin, LH, FSH.

  26. Endocinologic Diagnostic test PITUITARY PROBLEMS • Hypopituitarism: Free thyroxine index, LH, FSH, prolactin, oestradiol, testosterone, plasma cortisol (8am), 24hr urine cortisol, plasma IGF-1. Additional stress tests may be required (eg hypoglycaemia, metyrapone test to assess ACTH and cortisol status; glucagon, arginine or insulin hypoglycaemic test to assess GH axis). • Acromegaly: Plasma IGF-1, random plasma growth hormone profile. Consider glucose suppression test but usually IGF-I is a sufficient screen. • Short/tall stature: Plasma IGF-1, IGFBP-3, TSH and Free T4. • Short stature: Plasma growth hormone during stimulatory tests (clonidine, hypoglycaemia, sleep, exercise).

  27. با سپاس از توجه شما

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