Free Water Deficit in Hypernatremia
Free water deficit in hypernatremia or dehydration.
id
113
full_title
Free Water Deficit in Hypernatremia
short_title
Free Water Deficit in Hypernatremia
med_description
Calculates free water deficit by estimated total body water in a patient with hypernatremia or dehydration.
description
The Free Water Deficit in Hypernatremia calculates free water deficit in hypernatremia or dehydration by estimated total body water.
keywords
Free Water Deficit Hypernatremia, FW deficit, FW hypernatremia, Free water, free water deficit, free water hypernatremia, hypernatremia fw calc, fw calc, free water calc, free water hypernatremia calc, hypernatremia, hypernatremia online calc, FW deficit online, free water total water, free h2o, free h2o calc
complaint
[ "AMS", "Dizziness", "Weakness" ]
formula
Free water deficit, L = (% total body water, fraction)*(Weight, kg)*([Current sodium/Ideal sodium] – 1) where % total body water (TBW) is: Adult male: 60% (i.e., use 0.6 in the equation) Adult female: 50% (0.5) Elderly male: 50% (0.5) Elderly female: 45% (0.45) Child: 60% (0.6) This formula calculates the total solute in the patient’s total body water and then determines how much water needs to be added to dilute it to the desired serum sodium. Sufficient free water should be provided either orally or intravenously (e.g., 5% dextrose) to correct the serum sodium by up to 10 mEq/L in the first 24 hours.
evidence
measurements
[ { "name": "Weight", "unit": "wt", "error_min": "0.5", "error_max": "620", "warn_min": "0.5", "warn_max": "500", "conversion": "0.453592", "normal_max_si": "150", "normal_max_us": "330", "normal_min_si": "1", "normal_min_us": "2", "units_si": "kg", "units_us": "lbs" }, { "name": "Sodium", "unit": "na", "error_min": "100", "error_max": "200", "warn_min": "0", "warn_max": "170", "conversion": "1", "normal_max_si": "145", "normal_max_us": "145", "normal_min_si": "136", "normal_min_us": "136", "units_si": "mmol/L", "units_us": "mEq/L" } ]
information
refrences
{ "Clinical Practice Guidelines": [ { "href": "", "text": "" } ], "Manufacturer Website": [ { "href": "", "text": "" } ], "Original/Primary Reference": [ { "href": "https://www.ncbi.nlm.nih.gov/pubmed/10816188", "text": "Adrogue HJ and Madias NE. Primary Care: Hypernatremia. New England Journal of Medicine 2000; 342(20):1493-1499." }, { "href": "https://www.ncbi.nlm.nih.gov/pubmed/10824078", "text": "Adrogue HJ and Madias NE. Primary Care: Hyponatremia. New England Journal of Medicine 2000; 342(21):1581-1589." } ], "Other References": [ { "href": "https://ndt.oxfordjournals.org/content/17/7/1176.long", "text": "Barsoum NR and Levine BS. Current prescriptions for the correction of hyponatraemia and hypernatraemia: are they too simple?Nephrol. Dial. Transplant. (2002) 17 (7): 1176-1180 doi:10.1093/ndt/17.7.1176" } ], "Outcomes": [ { "href": "", "text": "" } ], "Validation": [ { "href": "", "text": "" } ], "Validations": [] }
pearls
This tool provides an estimate of free water deficit based on a patient's body weight; however, it may be inaccurate in patients with significant weight gain or loss (especially from fluid sources).
usecase
This tool should be used when a patient is hypernatremic but not volume depleted.
reasons
This formula should be used to estimate the amount of free water that needs to be provided (in addition to ongoing free water needs) to correct an elevated serum sodium.
next_advice
-
Hypernatremia is an elevation in serum sodium, indicating a free water deficit or dehydration.
-
In addition to calculating the free water deficit, the cause should be determined (e.g., loss of free water in the urine or stool, or lack of access to sufficient free water).
-
Patients may simultaneously be volume depleted and dehydrated.
-
If this is suspected, correct the volume deficit with isotonic fluids first before correcting the water deficit calculated here.
next_actions
next_management
Sufficient free water should be provided either orally or intravenously (using a solution such as 5% dextrose) to correct the serum sodium by up to 10 mEq/L in the first 24 hours.
diseases
[ "Hypernatremia" ]
instructions
published
2022-04-21T20:28:57.131Z
purpose
[ "Treatment", "Formula" ]
search_terms
[ "na", "sodium", "h20", "free water", "hypernatremia", "free water deficit", "dehydration" ]
seo
{ "keywords_en": "Free Water Deficit Hypernatremia, FW deficit, FW hypernatremia, Free water, free water deficit, free water hypernatremia, hypernatremia fw calc, fw calc, free water calc, free water hypernatremia calc, hypernatremia, hypernatremia online calc, FW deficit online, free water total water, free h2o, free h2o calc", "meta_description_en": "The Free Water Deficit in Hypernatremia calculates free water deficit in hypernatremia or dehydration by estimated total body water." }
specialty
[ "Critical Care", "Emergency Medicine", "Endocrinology", "Family Practice", "Geriatrics", "Hospitalist Medicine", "Internal Medicine", "Nephrology" ]
departments
[ "Endocrine and Metabolic", "Renal" ]
tags
[]
version_number
1
versions
[]
related
[ { "calcId": 10189, "short_title_en": "Body Fluid Balance Calculator", "slug": "body-fluid-balance-calculator-inputs-outputs" }, { "calcId": 50, "short_title_en": "Sodium Correction for Hyperglycemia", "slug": "sodium-correction-hyperglycemia" }, { "calcId": 480, "short_title_en": "Sodium Correction Rate in Hyponatremia/Hypernatremia", "slug": "sodium-correction-rate-hyponatremia-hypernatremia" } ]
ismed
false
section
[ "whenToUseViewed", "pearlsPitfallsViewed", "whyUseViewed", "nextStepsViewed", "evidenceViewed" ]
cleaned_departments
[ "endocrine", "urology" ]
cleaned_use
[ "This tool should be used when a patient is hypernatremic but not volume depleted." ]
pub
true