NANDA-I 2024-2026 edition · Reviewed November 2, 2026 by the editorial team
Diagnosis at a glance
| Code | 00421 |
|---|---|
| Label | Inadequate fluid volume |
| Before (2021-2023) | Former code 00027 |
| Spanish label | Volumen de líquidos inadecuado |
| Domain | 2. Nutrition |
| Class | 5. Hydration |
| Type | Problem-focused |
| Status | Current |
What changed in 2024-2026
In NANDA-I 2021-2023 it was "Deficient Fluid Volume," code 00027. In 2024-2026 it was revised: the label changed to "Inadequate Fluid Volume" and the code to 00421. It remains in Domain 2, Class 5 (Hydration). If your nursing program still uses the previous edition, you will see the old name; the clinical content is the same.
What it means
The patient has less circulating fluid than their body needs to maintain blood pressure, perfusion and organ function. It develops when losses (vomiting, diarrhea, fever, drains, third spacing) exceed intake, or when intake is poor.
Explanation written by our team. The official definition is in the NANDA-I 2024-2026 book.
When to use it
Clinical situations where it commonly shows up. The diagnosis is confirmed by your assessment, not by the medical diagnosis.
- Patients with vomiting or diarrhea who cannot tolerate oral intake.
- Acute pancreatitis, bowel obstruction or peritonitis, where fluid shifts out of the vessels into the abdomen and tissues.
- Prolonged fever or heavy sweating without adequate replacement.
- Older adults admitted with poor intake, confusion and concentrated urine.
- Postoperative patients with drains or tubes that are losing volume.
- Burns or hyperglycemia with polyuria.
What to assess
- Heart rate, blood pressure and orthostatic changes if the patient can sit up or stand safely.
- Hourly urine output relative to body weight: the minimum expected in adults is 0.5 mL/kg/h.
- Intake and output every shift, including emesis, liquid stools, drains and NG tube output.
- Daily weight at the same time on the same scale: 1 kg lost over a few days is roughly equal to 1 liter of fluid.
- Mucous membranes, capillary refill, skin temperature and level of consciousness.
- Available labs: hematocrit, sodium, potassium, BUN and creatinine.
- During fluid replacement, signs of fluid overload: crackles, dyspnea, jugular venous distension, falling SpO2.
Defining characteristics
Assessment findings that support the diagnosis. They go in the "as evidenced by" part of the statement.
- Intense thirst or, in older adults, no thirst despite poor intake.
- Dry oral mucosa and tongue.
- Resting heart rate above 100 bpm.
- Low blood pressure, or a systolic drop of 20 mmHg when moving from lying to sitting or standing.
- Urine output below 0.5 mL/kg/h for several hours.
- Dark, concentrated urine (high specific gravity).
- Capillary refill over 2 seconds and cool extremities.
- Rapid weight loss over a few days.
- Hematocrit or BUN elevated compared with previous values.
- Weakness, dizziness on standing, drowsiness or new-onset confusion.
Related factors
The causes nursing can act on. They go in the "related to" part of the statement.
- Losses from vomiting, diarrhea, sweating or drains that are not being replaced.
- Fluid intake below what the patient needs.
- Difficulty drinking due to dependence, dysphagia or nausea.
- Limited access to fluids: water pitcher out of reach, no help to drink.
- Inadequate knowledge of how much fluid they need and how to replace losses.
- Intake and output not recorded or incomplete.
At-risk populations
- Older adults, due to a blunted thirst response and lower total body water.
- Infants and young children with diarrhea or vomiting.
- People who depend on others to eat and drink.
- Patients NPO for long periods for tests or surgery.
- People exposed to extreme heat or prolonged exercise without fluid replacement.
Associated conditions
- Acute pancreatitis and bowel obstruction, with third spacing of fluid.
- Gastroenteritis with diarrhea and vomiting.
- Extensive burns.
- Hyperglycemia with polyuria, as in diabetic ketoacidosis.
- Diuretic therapy.
- Hemorrhage (also assess for risk for shock).
How to write it (PES)
Inadequate Fluid Volume related to unreplaced losses from vomiting and no oral intake for 24 hours as evidenced by HR 118 bpm, BP 96/60 mmHg, urine output of 0.25 mL/kg/h over the last 4 hours, dry oral mucosa, and capillary refill of 3 seconds.
Inadequate Fluid Volume (00421).
What explains the fluid shortfall and what you can act on: unreplaced losses, insufficient intake, barriers to drinking. The underlying disease (pancreatitis, gastroenteritis) is the associated condition, not the etiology.
The objective data that prove it: heart rate, blood pressure, urine output in mL/kg/h, mucous membranes, capillary refill, weight or labs. Avoid vague phrases like "patient is dehydrated."
Example written by our team for a fictional patient. Adapt it to your own patient's data. Build your statement with the PES generator.
Goals / expected outcomes
Written in measurable terms: what, how much and by when.
- Patient maintains urine output of at least 0.5 mL/kg/h in each of the next 12 hours.
- Heart rate drops below 100 bpm and systolic BP stays above 100 mmHg within 24 hours.
- Patient has moist oral mucosa and capillary refill under 2 seconds at 24 hours.
- 24-hour fluid balance is even or positive per the ordered goal, with no signs of fluid overload.
- Before discharge, patient or family explains how much fluid to drink and which signs of dehydration mean they need to seek care.
Nursing interventions and rationales
| Intervention | Rationale |
|---|---|
| Start a large-bore peripheral IV and administer the prescribed IV fluids at the ordered rate. | IV replacement is the fastest way to restore volume when oral intake is not possible. |
| Measure and record urine output every hour while the patient is unstable. | It is the most sensitive indicator that the kidneys are getting enough blood flow again. |
| Keep strict intake and output, including emesis, drains and stools. | Without measuring losses, you cannot calculate how much to replace. |
| Check heart rate, blood pressure and capillary refill every 1 to 2 hours at first, then as the patient's condition dictates. | Tachycardia is one of the first signs to improve or worsen with fluid replacement. |
| Auscultate lung fields and monitor for dyspnea and SpO2 during aggressive fluid replacement. | Replacing fluid too fast, especially in older adults or patients with heart disease, can cause pulmonary edema. |
| Administer the prescribed antiemetic or antidiarrheal and evaluate its effect. | Stopping the losses is as important as replacing them. |
| Weigh the patient every day at the same time and in the same clothing. | Allows reliable comparison and detects both fluid loss and overload. |
| Once oral intake is allowed, keep fluids within reach, offer small amounts frequently and help patients who need assistance to drink. | Many patients do not drink because they cannot reach the cup or do not ask for help. |
| Teach the patient and family to recognize thirst, dark urine, dizziness on standing and decreased urine output. | They can spot a new episode of dehydration at home before it becomes serious. |
NOC outcomes and NIC interventions
Outcomes (NOC) and interventions (NIC) that published sources link to this diagnosis. Pick the ones that fit your patient.
NOC outcomes
- 0601Fluid Balance
- 0602Hydration
- 0802Vital Signs
NIC interventions
- 4120Fluid Management
- 4130Fluid Monitoring
- 2080Fluid/Electrolyte Management
- 2020Electrolyte Monitoring
Linkages drawn from care plans published by health services, universities and nursing journals. Labels may vary depending on the NIC and NOC edition your facility uses.
Case study: Acute pancreatitis with persistent vomiting
Patient. 48-year-old man, 80 kg, admitted with acute gallstone pancreatitis. He has had epigastric pain and vomiting for 24 hours and has not been able to eat or drink.
Assessment
- HR 118 bpm, BP 96/60 mmHg, RR 22 breaths/min, temperature 37.8 °C (100.0 °F), SpO2 95% on room air.
- Five episodes of emesis in 24 hours, about 900 mL according to his family.
- Urine output of 80 mL over the last 4 hours (0.25 mL/kg/h), dark urine.
- Dry oral mucosa, coated tongue, capillary refill 3 seconds.
- Hematocrit 51% (previously 44%) and elevated BUN.
- Distended, tender abdomen; pain 7/10.
Nursing diagnosis
Inadequate Fluid Volume related to unreplaced losses from vomiting and no oral intake for 24 hours as evidenced by HR 118 bpm, BP 96/60 mmHg, urine output of 0.25 mL/kg/h, dry oral mucosa, capillary refill of 3 seconds, and hematocrit of 51%.
Goal
Patient reaches a urine output of at least 40 mL/h (0.5 mL/kg/h) and HR under 100 bpm within the first 12 hours of fluid replacement.
Interventions
- Start an 18-gauge peripheral IV and administer the prescribed crystalloids.
- Insert an indwelling urinary catheter per provider order and measure urine output hourly.
- Record intake and output, including emesis and NG tube output.
- Take vital signs hourly and auscultate lungs every 4 hours.
- Administer the prescribed antiemetic and assess nausea and vomiting after each dose.
- Notify the provider if urine output stays below 0.5 mL/kg/h for two hours in a row or crackles develop.
Evaluation
At 12 hours, urine output is 45-60 mL/h and HR is 96 bpm; no crackles. At 24 hours, mucous membranes are moist, hematocrit has dropped to 45% and the vomiting has stopped. The diagnosis stays active for another 24 hours, with I&O and urine output every 2 hours, and is resolved once he tolerates oral fluids.
How it differs from similar diagnoses
- Risk for inadequate fluid volume (00420): Risk for inadequate fluid volume: there is no tachycardia, oliguria or dry mucous membranes yet, but there are losses or low intake that could lead to them.
- Excessive fluid volume (00026): Excessive fluid volume is the opposite: edema, weight gain, crackles. It can develop if fluid replacement is overdone.
- Risk for impaired water-electrolyte balance (00491): Risk for impaired water-electrolyte balance focuses on sodium, potassium and other electrolytes, not on volume.
- Risk for shock (00205): If volume loss is large or rapid and organ perfusion is threatened, add Risk for shock.
Common mistakes
- Still using code 00027 in a care plan based on the 2024-2026 edition.
- Writing "related to pancreatitis" or "related to gastroenteritis": these are associated conditions; the etiology is unreplaced losses or low intake.
- Assuming a patient with edema cannot have inadequate fluid volume: in pancreatitis or cirrhosis there can be fluid in the tissues and too little inside the vessels.
- Not monitoring for fluid overload during volume replacement.
- Keeping the diagnosis open once urine output, heart rate and mucous membranes have returned to normal.
Used in these conditions
Other diagnoses in the Hydration class
Domain 2, Nutrition. See every diagnosis in this domain.
Frequently asked questions
What is the NANDA code for inadequate fluid volume?
00421, in Domain 2 (Nutrition), Class 5 (Hydration). It is the 2024-2026 revision of the old 00027.
What happened to the Deficient Fluid Volume 00027 nursing diagnosis?
It was revised in the 2024-2026 edition and is now called Inadequate Fluid Volume, code 00421. Use it instead of 00027 if your care plan follows the current edition.
Is inadequate fluid volume the same as dehydration or hypovolemia?
They are similar, but dehydration and hypovolemia are medical terms. The nursing diagnosis describes the patient's response and what nursing does to correct and monitor it.
What urine output indicates inadequate fluid volume?
In adults, less than 0.5 mL/kg/h for several hours in a row is a red flag. Always relate it to the patient's weight.
Can I use it for a pancreatitis patient with a distended abdomen?
Yes. In pancreatitis, fluid shifts out of the vessels into the abdomen and tissues, so there can be distension or edema with low circulating volume.
Study material: the explanation, characteristics, factors, examples and case study on this page were written by our editorial team. The official text for Inadequate fluid volume (00421) is in NANDA International Nursing Diagnoses: Definitions and Classification 2024-2026. This page does not replace clinical judgment or your facility's protocols.
Classification sources: NANDA-I 2024-2026, Thieme supplement · Elsevier summary of changes · Spanish edition table of contents · NOC/NIC: source 1. Reviewed November 2, 2026.