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Principles of Hormone Testing

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updated (2019) Learning Unit 4 Endocrinology module slide deck

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Principles of Hormone Testing

  1. 1. Principles of Hormone Testing All I really needed to know I learned in LU 3 Physiology :) Iris Thiele Isip Tan MD, MSc Professor, UP College of Medicine Chief, UP Medical Informatics Unit Baby steps by Kristina Alexanderson, https://flic.kr/p/att5j5
  2. 2. Pathologic Mechanisms of Endocrine Disease By Herbert L. Fred, MD & Hendrik A. van Dijk, http://commons.wikimedia.org/wiki/File%3AMyxedema_face.png By Jonathan Trobe, M.D. http://commons.wikimedia.org/wiki/File %3AProptosis_and_lid_retraction_from_Graves'_Disease.jpg Hormone Excess Deficiency Resistance
  3. 3. Explain the principle illustrated Answer question using learning points given Remember endocrine physiology Don’t forget by juliaf, http://www.freeimages.com/photo/729159 Question mark by 7rains, http://www.freeimages.com/photo/1323680 Black and white by plusverde, http://www.freeimages.com/photo/516694
  4. 4. CASE 1. A 38-year-old woman presents at your office for evaluation of hot flashes. She has been having 6-8 hot flashes per day for the past year and often wakes up at night drenched in sweat. She feels fatigued and irritable most of the time. She has not had menses for 12 months. Her FSH is 85 mIU/mL. FSH normal values Before puberty: 0 to 4.0 mIU/ml During puberty: 0.3 to 10.0 mIU/ml. Women who are still menstruating: 4.7 to 21.5 mIU/ml After menopause: 25.8 to 134.8 mIU/ml. Which of the following is true? A. She likely has premature ovarian failure. B. She is menopausal.
  5. 5. The normal range for most hormone is relatively broad, varying by a factor of two to tenfold. The correct normative database is an essential part of interpreting hormone tests. FSH normal values Before puberty: 0 to 4.0 mIU/ml During puberty: 0.3 to 10.0 mIU/ml. Women who are still menstruating: 4.7 to 21.5 mIU/ml After menopause: 25.8 to 134.8 mIU/ml.
  6. 6. CASE 2 An 28 y.o. woman gains 10 kg after receiving treatment for depression. Her psychiatrist is alarmed and does an 8 am cortisol Serum cortisol 26 (NV 4.3-22.4 ug/dL) Which of the following is true? A. She likely has Cushing’s syndrome. B. A suppression test should be done to prove cortisol excess.
  7. 7. http://www.endocrinesurgeon.co.uk/index.php/how-is-cushings-syndrome-diagnosed
  8. 8. Diagnostic tests take advantage of negative feedback loops. It is not uncommon for baseline hormone levels associated with pathologic endocrine conditions to overlap with the normal hormone range. DYNAMIC testing is useful.
  9. 9. CASE 3. A 55/M complains of loss of libido, erectile dysfunction, depression and lethargy. You think he has hypogonadism and order a serum testosterone assay. Which of the following is true? Blood draw for the testosterone assay should be done A. between 8-10 am B. between 8-10 pm
  10. 10. Recognition of hormonal rhythms is important for endocrine testing. Laboratory tests only represent a snapshot of endocrine function at the time that the blood sample was obtained.
  11. 11. CASE 4. President Eisenhower had a heart attack in 1955 and died 14 years later. The autopsy unexpectedly revealed a 1.5 cm pheochromocytoma in the left adrenal gland. Below is a record of his blood pressure readings. You would have ordered a a. 24-h urine metanephrine assay b. plasma metanephrine test
  12. 12. There are advantages and limitations in doing urine and blood measurements of hormones.
  13. 13. CASE 5. A 29-year-old pregnant woman in her 13th week of pregnancy was admitted for frequent vomiting of more than 10 times daily since her 11th week of pregnancy. She complains of nausea, dizziness, lethargy, loss of appetite and headache. She denies fever, palpitations, agitation, diarrhea and heat intolerance. She had no eye signs of Graves’ ophthalmopathy and no palpable goiter. Heart rate was 89 bpm and she had no tremors. FT4 35 (NV 11-24 pmol/L) TSH 0.1 (NV 0.3-3.8 mIU/mL). Which of the following is true? a. She should be given antithyroid therapy. b. She can be managed conservatively without antithyroid therapy.
  14. 14. Juan C. Galofre, Terry F. Davies. Autoimmune Thyroid Disease in Pregnancy: A Review. Journal of women’s health 2009;18(11):1847-1856 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2828163/pdf/jwh.2008.1234.pdf
  15. 15. Test results must be interpreted in conjunction with a clear understanding of the pathophysiology and natural history of suspected disorders. “ Fowler MJ, Pannone AF, Blevins Jr. South Med J 2002;95(5)
  16. 16. CASE 6. A 68-year-old woman is incidentally found to have a left adrenal mass, 2.8 cm in diameter, on abdominal computed tomography that was ordered to evaluate right lower abdominal discomfort (which has since resolved). Her medical history is notable only for hypertension that has been well controlled with hydrochlorothiazide, at a dose of 25 mg daily. She reports no sweating, palpitations, headache, weight gain, or proximal muscle weakness. Her physical examination is unremarkable. You would: a.Order for a 24-h urine metanephrine assay and 8 am cortisol. b.Order for 24-h urine metanephrine, plasma aldosterone and renin
  17. 17. Biochemical confirmation of endocrine disease precedes imaging.
  18. 18. CASE 7. A 32-year-old pregnant woman complains of palpitations on her 18th week of gestation. She has a palpable goiter. Which of the following is true? a.A free T4 and TSH should be done to assess thyroid function. b.T4, T3 and TSH should be done to assess thyroid function.
  19. 19. Juan C. Galofre, Terry F. Davies. Autoimmune Thyroid Disease in Pregnancy: A Review. Journal of women’s health 2009;18(11):1847-1856 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2828163/pdf/jwh.2008.1234.pdf
  20. 20. Remember that many hormones circulate in association with serum-binding proteins.
  21. 21. CASE 8. A dialysis patient is referred for high iPTH (intact parathyroid hormone) results. The referring physician did not do any other workup. You would - a. order a paired iPTH and serum calcium test. b. order a serum 25(OH)D level and serum calcium.
  22. 22. https://kleczekbiology.wikispaces.com
  23. 23. Simultaneous measurement of trophic and target hormones may help to determine the location of the abnormality.“ Klee G. Clinical Chemistry 1999;45(8B):1323-1330
  24. 24. Klee G. Clinical Chemistry 1999;45(8B):1323-1330
  25. 25. CASE 9. You are working up a 40-year-old female for Cushing’s syndrome. Urine free cortisol 450 (NV 55-248 nmol/day) repeat urine free cortisol 200 You will - a. Repeat urine free cortisol a third time. b. Request for a midnight salivary cortisol.
  26. 26. Harrison’s Principles of Internal Medicine
  27. 27. http://labtestsonline.org/understanding/features/reliability/start/1
  28. 28. http://www.med.uottawa.ca/sim/data/Images/Sen_spec.gif
  29. 29. Keep in mind the four indicators of reliability of laboratory testing: accuracy, precision, sensitivity, specificity
  30. 30. CASE 10. A 58-year-old man in the ICU is referred for low T3 and TSH but low normal T4. He was admitted for a stroke and is on dopamine and steroids. You would - a. give thyroid hormone replacement. b. do nothing.
  31. 31. Always ask what drugs can interfere with the results of hormone tests. Test abnormalities do not always reflect endocrine dysfunction. Some tests may be normal in the setting of real endocrine dysfunction.
  32. 32. Questions to Ask What are the key clinical issues? What sequence of tests would be optimal? What drugs should be discontinued before testing? What stabilizing, provocative or inhibitory procedures should the patient undergo before the specimen collection? Klee G. Clinical Chemistry 1999;45(8B):1323-1330
  33. 33. Efficacy of endocrine tests depends on Choice of tests Preparation of the patients Integrity of the specimens Quality of the measurements Validity of reference data Klee G. Clinical Chemistry 1999;45(8B):1323-1330
  34. 34. Principles of Hormone Testing All I really needed to know I learned in LU 3 Physiology :) Iris Thiele Isip Tan MD, MSc Professor, UP College of Medicine Chief, UP Medical Informatics Unit Baby steps by Kristina Alexanderson, https://flic.kr/p/att5j5

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