Updated: 12/11/2018

K-Sparing Diuretics

Topic
Review Topic
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Questions
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Evidence
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Overview
 

 
Snapshot
  • A 63-year-old man with a history of congestive heart failure presents with increased pedal edema and worsening orthopnea. He reports that he has been taking his lisinopril as prescribed and adhering to a low-salt diet. Physical exam shows 2+ pitting edema in the knees bilaterally and faint crackles on auscultation of the lungs. Left ventricular ejection fraction (LVEF) is measured by echocardiogram and found to be 33%. This is decreased from his last measurement of 38%. He is put on an additional medication. (Congestive heart failure exacerbations)
Spironolactone and Eplerenone
  • Mechanism
    • competitive aldosterone receptor antagonist in the cortical collecting tubule
      • reduces potassium secretion by decreasing activity of the epithelial sodium channel (ENAC) and the apical potassium channel
  • Clinical use
    • hyperaldosteronism
    • potassium wasting
      • from loop or thiazide diuretics
    • congestive heart failure (CHF)
      • decreases ventricular remodeling
      • reduces mortality
    • antiandrogenic
      • treatment for female hirsutism
  • Toxicity
    • hyperkalemia
      • can result in arrhythmias
    • spironolactone has antiandrogen effects  
      • causes gynecomastia 
      • eplerenone causes gynecomastia to a lesser extent 
Triamterene and Amiloride
  • Mechanism
    • blocks ENAC in the cortical collecting duct, thereby leading to decreased sodium reabsorption
      • indirectly reduces potassium secretion by creating a more positive luminal potential
      • indirectly decreases activity of the apical proton ATPase and reduces secretion of protons
    • does not cause anti-androgen effects
  • Clinical use 
    • congestive heart failure (CHF)
    • potassium wasting
    • lithium-induced nephrogenic diabetes insipidus
      • amiloride
  • Toxicity
    • hyperkalemia 
    • normal anion gap metabolic acidosis
 

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Questions (6)
Lab Values
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/L
Female: 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/mL
Female: 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/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative 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/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 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/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 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/min
Female: 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 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 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
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(M1.RL.13) A 70-year-old Caucasian male visits your office regularly for treatment of New York Heart association class IV congestive heart failure. Which of the following medications would you add to this man's drug regimen in order to improve his overall survival? Review Topic

QID: 100967
1

Spironolactone

60%

(46/77)

2

Amiloride

1%

(1/77)

3

Hydrochlorothiazide

12%

(9/77)

4

Furosemide

22%

(17/77)

5

Acetazolamide

0%

(0/77)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

(M1.RL.50) A 58-year-old man who had been complaining of increased shortness of breath with exertion and paroxysmal nocturnal dyspnea was started on a medical regimen to help stabilize his condition and relieve his fluid retention. Though his symptoms were improving, he noticed bilateral breast enlargement (Figure A) and returned to the clinic. The drug responsible for his breast enlargement also functions to do which of the following? Review Topic

QID: 101004
FIGURES:
1

Increase the PR interval on EKG

3%

(3/95)

2

Inhibit angiotensin converting enzyme

2%

(2/95)

3

Bind mineralcorticoid receptors

79%

(75/95)

4

Inhibit the Na+/K+/2Cl- triple transporter in the thick ascending limb of the loop of Henle

13%

(12/95)

5

Increase tubular fluid osmolarity

2%

(2/95)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 3
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