Snapshot A 30-year-old woman presents to her primary care physician for increased frequency of urinating, thirst, and urinating at night. She was in a car accident about a month ago, where she had head trauma. Since then, she reports that she has noticed this increased frequency of urination. At that time, head imaging had been normal. Her physician decides to conduct a vasopressin challenge. The results show decreased urine volume and increased urine osmolality. Based on these results, she decides to start the patient on desmopressin. (Central diabetes insipidis) Introduction Clinical definition diabetes insipidus (DI) characterized by excess free water loss and dilute urine Central vs Nephrogenic Diabetes Inspidus (DI) Central DI Nephrogenic DI Definition Failure to produce antidiuretic hormone (ADH) Insensitivity or resistance of the kidneys to ADH Etiology Pituitary tumor, where vasopressin is released Other pituitary injuries autoimmune disease trauma surgery ischemia Drugs lithium demeclocycline amphotericin B Congenital (rare) Electrolyte abnormalities hypercalcemia hypokalemia Pathogenesis ↓ ADH, resulting in increased extracellular fluid osmolarity ↑ ADH Vasopressin (DDAVP) challenge ↓ Urine volume and ↑ urine osmolality No change in urine volume or osmolality Presentation Symptoms polyuria polydipsia nocturia thirst Studies Serum labs ↑ serum osmolarity (central DI) electrolytes hypernatremia Other tests 24-hour urine studies best initial test ↓ urine osmolality ↓ urine sodium ↑ urine volume water deprivation challenge no change in urine osmolality or volume vasopressin challenge central DI ↓ urine volume and > 50% ↑ in urine osmolality with DDVAP nephrogenic DI lack of response to vasopressin Differential Primary polydipsia distinguishing factor hyponatremia after trial of desmopressin decreased urine output with water deprivation test Treatment Lifestyle hydration low sodium diet nephrogenic DI Medical desmopressin (DDAVP) mechanism ADH analog indication central DI hydrochlorothiazide mechanism indication indomethacin mechanism indication amiloride mechanism indication Complications Hypernatremia Dehydration
QUESTIONS 1 of 6 1 2 3 4 5 6 Previous Next Lab Values Blood Hematologic Cerebrospinal Sweat, Urine, and BMI Blood, Plasma, Serum Reference Range ALT 8-20 U/L Amylase, serum 25-125 U/L AST 8-20 U/L Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL Calcium, serum (Ca2+) 8.4-10.2 mg/dL Cholesterol, serum Rec: < 200 mg/dL Cortisol, serum 0800 h: 5-23 μg/dL //1600 h: 3-15 μg/dL 2000 h: ≤ 50% of 0800 h Creatine kinase, serum Male: 25-90 U/LFemale: 10-70 U/L Creatinine, serum 0.6-1.2 mg/dL Electrolytes, serum Sodium (Na+) 136-145 mEq/L Chloride (Cl-) 95-105 mEq/L Potassium (K+) 3.5-5.0 mEq/L Bicarbonate (HCO3-) 22-28 mEq/L Magnesium (Mg2+) 1.5-2.0 mEq/L Estriol, total, serum (in pregnancy) 24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL 28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL Ferritin, serum Male: 15-200 ng/mLFemale: 12-150 ng/mL Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL Female: premenopause: 4-30 mIU/mL midcycle peak: 10-90 mIU/mL postmenopause: 40-250 pH 7.35-7.45 PCO2 33-45 mmHg PO2 75-105 mmHg Glucose, serum Fasting: 70-110 mg/dL2-h postprandial:<120 mg/dL Growth hormone - arginine stimulation Fasting: <5 ng/mLProvocative stimuli: > 7ng/mL Immunoglobulins, serum IgA 76-390 mg/dL IgE 0-380 IU/mL IgG 650-1500 mg/dL IgM 40-345 mg/dL Iron 50-170 μg/dL Lactate dehydrogenase, serum 45-90 U/L Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL Female: follicular phase: 5-30 mIU/mL midcycle: 75-150 mIU/mL postmenopause 30-200 mIU/mL Osmolality, serum 275-295 mOsmol/kd H2O Parathyroid hormone, serume, N-terminal 230-630 pg/mL Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L Phosphorus (inorganic), serum 3.0-4.5 mg/dL Prolactin, serum (hPRL) < 20 ng/mL Proteins, serum Total (recumbent) 6.0-7.8 g/dL Albumin 3.5-5.5 g/dL Globulin 2.3-3.5 g/dL Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h Thyroxine (T4), serum 5-12 μg/dL Triglycerides, serum 35-160 mg/dL Triiodothyronine (T3), serum (RIA) 115-190 ng/dL Triiodothyronine (T3) resin uptake 25%-35% Urea nitrogen, serum 7-18 mg/dL Uric acid, serum 3.0-8.2 mg/dL Hematologic Reference Range Bleeding time 2-7 minutes Erythrocyte count Male: 4.3-5.9 million/mm3Female: 3.5-5.5 million mm3 Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/hFemale: 0-20 mm/h Hematocrit Male: 41%-53%Female: 36%-46% Hemoglobin A1c ≤ 6 % Hemoglobin, blood Male: 13.5-17.5 g/dLFemale: 12.0-16.0 g/dL Hemoglobin, plasma 1-4 mg/dL Leukocyte count and differential Leukocyte count 4,500-11,000/mm3 Segmented neutrophils 54%-62% Bands 3%-5% Eosinophils 1%-3% Basophils 0%-0.75% Lymphocytes 25%-33% Monocytes 3%-7% Mean corpuscular hemoglobin 25.4-34.6 pg/cell Mean corpuscular hemoglobin concentration 31%-36% Hb/cell Mean corpuscular volume 80-100 μm3 Partial thromboplastin time (activated) 25-40 seconds Platelet count 150,000-400,000/mm3 Prothrombin time 11-15 seconds Reticulocyte count 0.5%-1.5% of red cells Thrombin time < 2 seconds deviation from control Volume Plasma Male: 25-43 mL/kgFemale: 28-45 mL/kg Red cell Male: 20-36 mL/kgFemale: 19-31 mL/kg Cerebrospinal Fluid Reference Range Cell count 0-5/mm3 Chloride 118-132 mEq/L Gamma globulin 3%-12% total proteins Glucose 40-70 mg/dL Pressure 70-180 mm H2O Proteins, total < 40 mg/dL Sweat Reference Range Chloride 0-35 mmol/L Urine Calcium 100-300 mg/24 h Chloride Varies with intake Creatinine clearance Male: 97-137 mL/minFemale: 88-128 mL/min Estriol, total (in pregnancy) 30 wks 6-18 mg/24 h 35 wks 9-28 mg/24 h 40 wks 13-42 mg/24 h 17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 hFemale: 2.0-8.0 mg/24 h 17-Ketosteroids, total Male: 8-20 mg/24 hFemale: 6-15 mg/24 h Osmolality 50-1400 mOsmol/kg H2O Oxalate 8-40 μg/mL Potassium Varies with diet Proteins, total < 150 mg/24 h Sodium Varies with diet Uric acid Varies with diet Body Mass Index (BMI) Adult: 19-25 kg/m2 Calculator ( ) xy AC 7 8 9 ÷ 4 5 6 × 1 2 3 - 0 . = + Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK You have 100% on this question. Just skip this one for now. Take This Question Anyway (M1.EC.13.65) A 23-year-old male presents with complaints of polydipsia and frequent, large-volume urination. Laboratory testing does not demonstrate any evidence of diabetes; however, a reduced urine osmolality of 120 mOsm/L is measured. Which of the following findings on a desmopressin test would be most consistent with a diagnosis of central diabetes insipidus? Review Topic | Tested Concept QID: 100366 Type & Select Correct Answer 1 Reduction in urine osmolality to 60 mOsm/L following vasopressin administration 3% (1/30) 2 Reduction in urine osmolality to 110 mOsm/L following vasopressin administration 3% (1/30) 3 Increase in urine osmolality to 130 mOsm/L following vasopressin administration 3% (1/30) 4 Increase in urine osmolality to 400 mOsm/L following vasopressin administration 83% (25/30) 5 No detectable change in urine osmolality following vasopressin administration 3% (1/30) L 2 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4