Hypernatremia

Revision as of 19:44, 9 December 2011 by Jack Khouri (talk | contribs)
Jump to navigation Jump to search

Hypernatremia Microchapters

Home

Patient Information

Overview

Historical perspective

Classification

Pathophysiology

Causes

Differentiating Hypernatremia from other Diseases

Epidemiology and Demographics

Risk Factors

Natural History, Complications and Prognosis

Diagnosis

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

CT

MRI

Other Diagnostic Studies

Other Imaging Findings

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

Case Studies

Case #1

Hypernatremia On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Hypernatremia

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Hypernatremia

CDC on Hypernatremia

Hypernatremia in the news

Blogs on Hypernatremia

Directions to Hospitals Treating Hypernatremia

Risk calculators and risk factors for Hypernatremia

Hypernatremia
Sodium
ICD-10 E87.0
ICD-9 276.0
DiseasesDB 6266

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Assistant Editor(s)-In-Chief: Jack Khouri

Overview

Pathophysiology

Causes

Differential Diagnosis of Associated Disorders and Causes of Hypernatremia

Cardiovascular No underlying causes
Chemical / poisoning No underlying causes
Dermatologic Burns, Excessive sweating
Drug Side Effect diuretics
Ear Nose Throat No underlying causes
Endocrine Adrenal, Diabetes Insipidus, Congenital Adrenal Hyperplasia, Conn's Syndrome,Cushing's Syndrome, Ectopic adrenocorticotropic hormone (ACTH) production, Hyperaldosteronism, Hyperglycemia, Hyperlipidemia, Thyrotoxicosis
Environmental No underlying causes
Gastroenterologic Gastrointestinal losses (diarrhea, vomiting), inability to swallow water (physical limitation)
Genetic No underlying causes
Hematologic No underlying causes
Iatrogenic Inappropriate IV fluids
Infectious Disease Fever
Musculoskeletal / Ortho No underlying causes
Neurologic Essential hypernatremia, Dementia, Coma, hypothalamic lesion, inability to recognize thirst for water
Nutritional / Metabolic ingestion of large quantities of sodium (seawater), decreased protein intake
Obstetric/Gynecologic No underlying causes
Oncologic Multiple Myeloma
Opthalmologic No underlying causes
Overdose / Toxicity Alcoholism
Psychiatric No underlying causes
Pulmonary Sarcoidosis, Hyperventilation
Renal / Electrolyte High urea levels with renal failure, Hypercalcemia, Hypokalemia, Osmotic diuresis, Peritoneal dialysis,Diuresis phase of acute renal failure
Rheum / Immune / Allergy Sjogren's Syndrome
Sexual No underlying causes
Trauma No underlying causes
Urologic No underlying causes
Miscellaneous Amyloidosis

Diagnosis

Diagnosing the etiology of hypernatremia is essential. Symptoms, urine osmolarity and water deprivation studies are all helpful.

History and Symptoms

Symptoms

Clinical manifestations of hypernatremia can be subtle, consisting of lethargy, weakness, irritability, and edema. With more severe elevations of the sodium level, seizures and coma may occur.

Severe symptoms are usually due to acute elevation of the plasma sodium concentration to above 158 mEq/L, which corresponds to an osmolar gradient of 30-35 mEq/kg between plasma and brain. Beyond that level, the rapid reduction of brain volume can cause rupture of cerebral veins leading to intracerebral and subarachnoid hemorrhage. Values above 180 mEq/L are associated with a high mortality rate, particularly in adults. However such high levels of sodium rarely occur without severe coexisting medical conditions.

To note that if hypernatremia progresses over more than 24 hours, the brain adapts rapidly to plasma hyperosmolarity by the intracellular accumulation of many osmolytes such as amino acids (eg, glutamate).

History

A detailed history is important for the diagnosis of the etiology of hypernatremia. It should mention any history of diabetes insipidus, hyperaldosteronism, Cushing's disease, neurologic disease, seizure disorder, malabsorptive disease and ingestion of excess sodium salts. Current diarrhea, burns, exercise (increased sweating), polyuria and polydypsia should be emphasized. Drug history should include diuretic use or ingestion of osmotic agents (eg, mannitol, lactulose).

Labs and Procedures

  • Urine osmolarity is essential to differentiate renal from extrarenal water loss. A normal kidney would respond to hypernatremia by excreting a highly concentrated urinewith a urine osmolality >800 mosmol/kg.
    • Urine osmolarity <300 mosm/kg is consistent with renal water losses due to diabetes insipidus (neurogenic vs nephrogenic).
    • Urine osmolarity between 300 and 800 mosm/kg indicates partial diabetes insipidus or osmotic diuresis.
    • Urine osmolarity >800 mosm/kg points out to insensible or GI losses, increased sodium ingestion or primary hypodypsia.
  • The water deprivation test
    • The objective of this test is to distinguish the origin of diabetes insipidus (DI).
    • Desmopressin (AVP), a synthetic analogue of vasopressin, is effective in patients with central DI.
    • Upon AVP adminstration, patients will have different urine osmolarities depending on their DI etiology.
    • Patients with central DI have intact kidney response to vasopressin and will have a substantial increase in urine osmolarity in response to water deprivation and desmopressin administrarion.
    • Patients with nephrogenic DI have little or no increase in urine osmolarity in response to AVP.
    • Patients with partial central DI show an increase in urine osmolarity of >10%.

Treatment

  • The cornerstone of treatment is administration of free water to correct the relative water deficit. Water can be replaced orally or intravenously.
  • Overly rapid correction of hypernatremia is potentially very dangerous. As we mentioned before, The body (in particular the brain) adapts to the higher sodium concentration. Rapidly lowering the sodium concentration with free water, once this adaptation has occurred, causes water to flow into brain cells and causes them to swell (cerebral edema). This can lead to cerebral edema, potentially resulting in seizures, permanent brain damage, or death. Central pontine myelinolysis can also occur with over rapid correction of the sodium which should be about 0.5 meq/l/hour and no more than 1 meq per hour. Significant hypernatremia should be treated carefully by a physician or other medical professional with experience in treatment of electrolyte imbalances.
  • Free Water deficit (L)= 0.6 x (body weight(kg)) x ((plasma[Sodium]/140)-1)
  • Central DI should be treated with desmopressin and drugs that increase vasopressin release eg Clofibrate.
  • Nephrogenic DI can be treated with Thiazide diuretics, low salt and low protein diet.

See also

Template:Endocrine, nutritional and metabolic pathology


Template:WikiDoc Sources