Commonly taught laboratory reference ranges organised by panel, with the nursing significance of a result outside each range and guidance on interpreting values in written coursework rather than listing them.
How ranges are used, and the caveat that governs all of them
A table of nursing lab values is useful and is also the part of the subject most likely to be misused. Two things have to be said before any figure appears.
First, reference ranges differ between laboratories. They depend on the analyser, the assay, the population the laboratory serves and the units in use. The range printed alongside the result on the report is the one that applies to that sample, and it overrides any figure learned from a table, including this one. Coursework that quotes a range should say which source it came from.
Second, a value is rarely interpreted alone. A sodium is read alongside the fluid status, a urea alongside the creatinine, a haemoglobin alongside whether the patient is bleeding now or has been anaemic for months. The clinically significant finding is much more often a trend across several results than a single number crossing a line.
The ranges below are the ones commonly taught for adults in nursing programmes, given so that the surrounding discussion has something concrete to refer to. Paediatric, neonatal and pregnancy ranges differ substantially and are not covered here.
Full blood count
The count that answers three separate questions: is the patient anaemic, are they mounting or losing a response to infection, and can they clot.
Haemoglobin, commonly cited as approximately 13.5 to 17.5 grams per decilitre in adult men and 12.0 to 15.5 in adult women. A low value means reduced oxygen carrying capacity, and the nursing consequence is exertional breathlessness, tachycardia and fatigue. How fast it fell matters more than the figure: a patient who has been at 9 for months tolerates it far better than one who reached 9 this morning.
White cell count, commonly cited as approximately 4,500 to 11,000 per microlitre. A raised count suggests infection or inflammation. A low count is the more dangerous finding in a patient receiving chemotherapy, because it means the patient cannot mount the response, and the usual signs of infection may be muted or absent. In sepsis either direction is possible, and a low count carries the worse outlook, which is a point plans built on recognising the deteriorating septic patient should not gloss over.
Platelets, commonly cited as approximately 150,000 to 400,000 per microlitre. Falling platelets raise bleeding risk and change nursing practice directly: pressure held longer after venepuncture, attention to bruising, care with razors and firm toothbrushes.
Electrolytes and the basic metabolic panel
The panel most often responsible for a clinical decision on the ward, and the one where a nurse is most likely to be the first person to see a dangerous result.
Sodium, commonly cited as approximately 135 to 145 millimoles per litre. Sodium is a water problem far more often than a salt problem. A low sodium usually reflects relative water excess, and its clinical expression is neurological: confusion, headache, and at low enough levels, seizures. Rate of change matters as much as the value, and rapid correction carries its own risk.
Potassium, commonly cited as approximately 3.5 to 5.0 millimoles per litre. The narrowest clinically important range on the panel, because both directions affect cardiac conduction. Low potassium is a common consequence of diuretic therapy, which is why it is monitored in the fluid-driven heart failure plan. High potassium is the more immediately dangerous, and any result at the extremes belongs in the critical value pathway rather than in a routine handover.
Chloride, approximately 98 to 106 millimoles per litre, and bicarbonate, approximately 22 to 28 millimoles per litre. Read together with the other electrolytes, these describe the acid-base picture that an arterial blood gas confirms.
Calcium, total calcium commonly cited as approximately 8.5 to 10.5 milligrams per decilitre. Interpreted against albumin, because a substantial share is protein bound and a low albumin lowers the total without lowering the physiologically active fraction.
Glucose, fasting commonly cited as approximately 70 to 99 milligrams per decilitre. Read in context: a value in a patient on insulin, a patient who is nil by mouth, or a patient who is acutely unwell is interpreted quite differently in each case.
Kidney function
Two numbers that mean different things and are read as a pair.
Blood urea nitrogen, commonly cited as approximately 7 to 20 milligrams per decilitre, and creatinine, approximately 0.6 to 1.2 milligrams per decilitre in men and 0.5 to 1.1 in women.
Urea rises with dehydration, with gastrointestinal bleeding and with a high protein load as well as with kidney impairment, so it is a sensitive but non-specific marker. Creatinine is more specific to filtration but is generated from muscle, which means an older patient with little muscle mass can have significant impairment at a creatinine that still reads as normal. A urea rising faster than the creatinine points toward a volume problem rather than intrinsic kidney disease, which is why the two are quoted together and why quoting one alone in a write-up invites the question of where the other is.
Estimated glomerular filtration rate is calculated rather than measured, and is reported with the creatinine. It is the figure used to adjust medication doses, which makes it directly relevant to the checks performed during medication administration rather than a purely medical concern.
Liver function and coagulation
Alanine aminotransferase and aspartate aminotransferase are enzymes released when liver cells are damaged, so they indicate injury rather than function. Commonly cited ranges are roughly 7 to 56 and 10 to 40 units per litre respectively.
Alkaline phosphatase, approximately 44 to 147 units per litre, rises with obstruction of the biliary system and also with bone turnover, so it is interpreted alongside the rest of the panel rather than alone.
Bilirubin, total commonly cited as approximately 0.1 to 1.2 milligrams per decilitre. The value at which jaundice becomes visible is well above the upper limit of normal, so a raised bilirubin is frequently a laboratory finding before it is a clinical one.
Albumin, approximately 3.5 to 5.0 grams per decilitre. Low albumin reduces plasma oncotic pressure and contributes to oedema, affects the interpretation of calcium, and alters the free fraction of drugs that bind to it. It is also a slow marker, reflecting weeks rather than days.
Prothrombin time, approximately 11 to 13.5 seconds, and the international normalised ratio, approximately 0.8 to 1.1 in a patient not receiving anticoagulation. These measure how long clotting takes, and a prolonged result in a patient who is not anticoagulated is a finding rather than an expected result.
Arterial blood gas
The panel that tells you whether the patient is compensating and whether they are tiring, which no other test does as directly.
Arterial pH, approximately 7.35 to 7.45. Arterial carbon dioxide tension, approximately 35 to 45 millimetres of mercury. Arterial oxygen tension, approximately 80 to 100 millimetres of mercury. Bicarbonate, approximately 22 to 26 millimoles per litre. Oxygen saturation, approximately 95 to 100 per cent on room air.
The reading is done in a fixed order: look at the pH to see which way the disturbance runs, then at the carbon dioxide to see whether the cause is respiratory, then at the bicarbonate to see whether the cause is metabolic, then decide whether the other system has compensated.
The nursing significance is in what a rising carbon dioxide means in a breathless patient. A patient working hard to breathe usually blows off carbon dioxide, so a low value is expected. A normal or rising value in that patient signals exhaustion rather than improvement, and it is one of the few laboratory results that should change nursing behaviour immediately. It matters in exactly the population covered by our plan separating gas exchange from airway clearance.
Values that change what happens in the next few minutes
Some results are not ordinary abnormalities. Every laboratory maintains a critical value list, and results on it are telephoned rather than reported, because they require a response now.
The categories are consistent even where the exact thresholds are local: potassium at either extreme, glucose very low or very high, sodium severely deranged, haemoglobin very low, platelets very low, and any result indicating a life-threatening acid-base disturbance. Positive blood cultures and certain coagulation results are handled the same way.
The practical point for a student is that knowing a result belongs on that list matters more than recalling the precise threshold, because the threshold is written down and the recognition is not. The nursing action is to acknowledge the result, record who it was received from and when, escalate to the treating team, and document the response. That is the same structured escalation used for any urgent clinical finding, and the situation, background, assessment and recommendation format is what stops the message drifting into narrative.
Using laboratory values in written coursework
In assessed work the number earns nothing. What earns the mark is what you do with it, and there are three habits that separate a strong write-up from a list.
Interpret rather than report. "Potassium 2.9 millimoles per litre" is a transcription. "Potassium 2.9 millimoles per litre, below the reference range, in a patient receiving a loop diuretic; hypokalaemia at this level affects cardiac conduction, so continuous cardiac monitoring, review of the diuretic and prescribed replacement were indicated" is an interpretation. The second contains the first.
Group the values that belong together. Report urea with creatinine, calcium with albumin, haemoglobin with the clinical picture of bleeding or chronic anaemia. Presenting a panel as an undifferentiated list signals that the relationships were not recognised.
Attach the values to the nursing action. This is what converts a results section into evidence for a care plan. A laboratory result that appears in the assessment and never reappears in the interventions has not been used. The objective section of a progress note is where this discipline is enforced most visibly, and the same expectation runs through a full case study write-up.
Finally, cite the source of any range you quote and state that local ranges govern. It costs one sentence and it is the difference between a figure that is defensible and one that is asserted. Students working on an assignment that turns on laboratory interpretation can ask a nursing writer to review the analysis.