Hyponatremia differential diagnosis

Hyponatremia Microchapters
Home
Patient information
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Hyponatremia from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
Diagnostic Study of Choice
History and Symptoms
Physical Examination
Laboratory Findings
Electrocardiogram
X-ray
Echocardiogram or Ultarsound
CT scan
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Surgery
Primary Prevention
Secondary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
Case #1
Hyponatremia differential diagnosis On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
American Roentgen Ray Society Images of Hyponatremia differential diagnosis All Images X-rays Echo & Ultrasound CT Images MRI
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Hyponatremia differential diagnosis
CDC on Hyponatremia differential diagnosis
Hyponatremia differential diagnosis in the news
Blogs on Hyponatremia differential diagnosis
Directions to Hospitals Treating hyponatremia
Risk calculators and risk factors for Hyponatremia differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Iqra Qamar M.D.[2] Saeedeh Kowsarnia M.D.[3]

Overview

Different disorders which cause hyponatremia are differentiated based on volume status, clinical presentation, serum and urine osmolality.

Differentiating etiologies of Hyponatremia

Disease	Clinical manifestations											Paraclinical Findings
	Symptoms and Signs											Lab Findings
	Muscle weakness/ Cramps	Oliguria	Vomiting/ Diarrhea	Volume status	JVP	Edema	Crackles	Ascites	Tachycardia	Hypotension	Dry mucous membranes	Urine Analysis			Serum Osmolality	ADH levels
												Urine Na	Urine Osm	FeNa
Renal failure	+/-	+/-	-	Hypervolemic	+	+	+	+	-	-	-	>20	-	>1%	↓	Normal or ↑
Congestive heart failure	+/-	-	-	Hypervolemic	+	+	+	+	-	-	-	<10	-	<1%	↓	↑
Cirrhosis	+/-	-	-	Hypervolemic	+	+	+	+	-	-	-	<10	-	<1%	↓	↑
SIAD/ SIADH	+/-	-	-	Euvolemic	-	-	-	-	-	-	-	-	>100	-	↓	↑
Hypothyroidism	+/-	-	-	Euvolemic	-	-	-	-	-	-	-	-	>100	-	↓	↑
Adrenal insufficiency	+/-	-	-	Euvolemic	-	-	-	-	-	-	-	-	>100	-	↓	↑
Psychogenic polydipsia	+/-	-	-	Euvolemic	-	-	-	-	-	-	-	-	<100	-	↓	↑
Beer drinker's potomania	+/-	-	-	Euvolemic	-	-	-	-	-	-	-	-	<100	-	↓	↓
Pregnancy	+/-	-	-	Euvolemic	-	-	-	-	-	-	-	-	Variable	-	↓	↓
Anorexia (Chronic malnutrition)	+/-	-	-	Euvolemic	-	-	-	-	-	-	-	-	Variable	-	↓	-
Diuretic induced hyponatremia	+/-	+	-	Hypovolemic	-	-	-	-	+	+	+	>20	-	>1%	↓	-
Non oliguric ATN	+/-	-	-	Hypovolemic	-	-	-	-	+	+	+	>20	-	>1%	↓	-
Diseases causing 3rd spacing (Pancreatitis, SBO)	+/-	+	+/-	Hypovolemic	-	-	-	-	+	+	+	<10	-	<1%	↓	-
Gastroenteritis	+/-	+	+	Hypovolemic	-	-	-	-	+	+	+	<10	-	<1%	↓	-
Sweating	+/-	+	-	Hypovolemic	-	-	-	-	-	+/-	+/-	<10	-	<1%	↓	-
Cerebral salt-losing syndrome	+/-	-	+/-	Euvolemic	-	-	-	-	-	+/-	-	>20	>100	> 1%	↓	-

Differentiation between SIAD and Cerebral-salt wasting syndrome:

Condition	Urine sodium	Urine volume	Blood pressure	Serum uric acid	Serum urea concentration	Clinical features
SIAD	> 30	↔ , ↓	↔	↓	↔ , ↓	No sign of hypovolemia, Normal or positive fluid balance with absence of weight loss, CVP > 6 cm of water
Cerebral-salt-wasting syndrome	>> 30	↑	↔ , orthostatic hypotension	↓	↔ , ↑	Clinical signs of hypovolemia, such as hypotension, dry mucous membranes, tachycardia, or postural hypotension, Negative fluid balance or weight loss, CVP < 6 cm of water

Laboratory Findings

Approach to differential diagnosis

Biochemical evaluation for finding the etiologies of hyponatremia :

The unnamed parameter 2= is no longer supported. Please see the documentation for {{columns-list}}.

2

Serum Na ≤ 135 meq/L

Check for: • Serum osmolality • Urine osmolality • Urea • Glucose • Urine chloride • Urine Na

Normotonicity 275–295 mOsm/kg •Hyperlipidemia •Hyperproteinemia •Glycine

Hypertonicity > 295 mOsm/kg • Glucose • Mannitol • Glycine • Severe azotemia

Hypotonicity <275 mOsm/kg

UOsm < 100mOsm/kg

UOsm > 200mOsm/kg

UOsm 100–200mOsm/kg

Conditions •Polydipsia •↓ solute excertion (Beer potomania ,Tea & toast diet)

Conditions •Polydipsia •↓ solute excertion (Beer potomania ,Tea & toast diet) •Rule out SIAD

Hypovolemia Based on history & physical exam

Hypervolemia

Euvolemia

UNa < 30 mEq/L

Variable UNa

UNa > 30 mEq/L

UNa < 30 mEq/L

UNa > 30 mEq/L

Variable UNa

UNa < 20 mEq/L

> 20 UNa < 40 mEq/L

UNa > 40 mEq/L

Extrarenal losses •Vomiting (Ucl ↓) •Diarrhea •Pancreatitis •Sweating •Small bowel obstruction

Variable UNa •Diuretic use Discontinue diuretics if UNa is still abnormal

Renal losses •Osmotic diuresis (glucose, urea,bicarbonaturia) •Salt-Iosing nephropathy •Addison disease •CSW

Conditions •Heart failure •Liver disease •Nephrotic syndrome

Conditions •Chronic kidney disease •Diuretic use in: Heart failure Liver disease Nephrotic syndrome

Discontinue diuretics if PNa normalize it's not SIAD if it's not normalized

Probable hypovolemia

Hypovolemia or euvolemia

•Probable euvolemia •SIAD •Cortisol deficiency •Hypothyroidism

Administer 0.9% saline

Normalize PNa

Administer 1–2 L 0.9% saline

Failure to normalize PNa

Hypovolemia

PNa decreases or no change

PNa increases

Decreasing UOsm

No change in UOsm but UNa increases

SIAD

No change in UOsm but UNa increases

Decreased UNa

Hypovolemia

Salt-depleted SIAD

Hypovolemia

Decreasing Uosm

Administer additional saline

No change in UOsm but UNa increases

Salt-depleted SIAD