Knowing the normal range of ‘lab values’ is intrinsic to a nurse’s career. Health of the human body can be determined by knowing the lab values which measure certain variables of the body that help to asses and determine a variety of abnormalities and diseases. Maintaining the health records of patients is an important part of the duties of an LPN as well as RN, and this cannot be possible without knowing the normal range of and analysis of lab values.
Why is it important to know them?
NCLEX does ask qusetions regarding lab values whcich focus on distinguishing the correct or standard value from the non standard ones. You need to know them well, but not only sit and cram them like parrot. The underlying motive of such questions is more than just asking you the correct values, sometimes the questions are twisted in order to ask you the implications or moed of action henceforth after knowing a patient’s report.
Moreover you need to know that there is no ‘one’ main standard of values that you need to know since tey can differ from hospital to hospital. So, you just need to know the range and be able to deduce and analyse the information if the values fallout from the normal range. Remember, that it is the patient’s nurse who is the first person to see a patient’s reports and has to immediately bring it to the notice of the doctor, so of course this part cannot be overlooked.
The trick to remembering them?
It is not a cake walk to remember ALL the lab values that you have been taught in a nursing school! While preparing for the NCLEX liek all other parts of your content you need to make choices here too. Eliminate the non essential ones. Now the question arises that which are the essential ones?
Often repeated questions will let you know this. the basic ones everyone needs to know, make a choice for what more? Some lab values are often indirectly asked in case studies wher you are not requirsed to tell teh correct valu or its range but you need to assess and take a decision. One more trick is that you can do a practice of lots of good case studies nad you’ll leran tehma as you practice.
Otehr values that just need to be known and are’nt even often used in case studies, they need to be simply learnt and for that you can revise them again an again to remember them or mnemonics can be of help.
Also, know about the implications of any lab value that falls out of range. In either of the case it being too low or too high, knowing what condition it would trigger in a patient will also help you remember better.
EDITOR’S NOTE: A good NCLEX review course will make this easy for you. It should be providing yo with tricks and tactics to remember them, relevant case studies and interpretation skills. We recommend Extended (3 month access) NCLEX-RNÆ Test Prep Track and Extended (3 month access) NCLEX-PNÆ Test Prep Track.
A short list of ‘Lab Values ‘ that are important for you to know. Target NCLEX!
Arterial Blood gases
pH 7.35 – 7.45
PaCO2 35 – 45
HCO3 22 – 26BUN 5 – 20
Hemoglobin: 12–16 g/dL Women; 14–18 g/dL Men
Hematocrit: 37 – 48% Women; 45 – 52% Men
Glucose 70 – 100
• Ammonia: 15-50 µmol/L
• Chloride: 95-105 mmol/L
• Creatinine: 0.8-1.3 mg/dL
• Blood urea nitrogen: 8-21 mg/dL
• Ferritin: 12-300 ng/mL (men), 12-150 ng/mL (women)
• Glucose: 65-110 mg/dL
• Inorganic phosphorous: 1-1.5 mmol/L
• Ionized calcium: 1.03-1.23 mmol/L
• Magnesium: 1.5-2 mEq/L
• Phosphate: 0.8-1.5 mmol/L
• Potassium: 3.5-5 mmol/L
• Pyruvate: 300-900 µg/dL
• Sodium: 135-145 mmol/L
• Total calcium: 2-2.6 mmol/L
• Total iron-binding capacity: 45-85 µmol/L
• Total serum iron: 65-180 µg/dL (men), 30-170 µg/dL (women)
• Transferrin: 200-350 mg/dL
• Urea: 1.2-3 mmol/L
• Uric acid: 0.18-0.48 mmol/L
• Zinc: 70-100 µmol/L
Interpretation from ‘Lab values’!
We have cited two examples to let you know how these are used for diagnosis.
1. Potassium levels aid in diagnosing disorders such as acidosis, renal failure, and dehydration. They are used to monitor the effectiveness of therapeutic interventions implemented.
Increased potassium K+ :acute renal disease, burns, crushing injuries, adrenal insufficiency, dehydration, anorexia nervosa, excessive intake caused by specific drugs (potassium penicillin), salt substitute, or, the most common, too rapid infusion of intravenous (IV) solution containing potassium.
Decreased K+ :renal loss (due to diuretics), loss from the gastrointestinal (GI) tract via nasogastric (NG) tube, vomiting or diarrhea, reduced potassium intake, hypomagnesemia, endocrine causes.
D. Treatment implications.
Critical values may lead to fatal cardiac arrhythmias.
Removal of excess potassium per physician’s orders.
a. Administer diuretics if kidney function is adequate.
b. Administer exchange resins through NG tube or via sodium Kayexalate (polystyrene sulfonate) enema.
c. Administer hypertonic IV glucose with insulin as ordered—moves potassium back into cells.
d. Administer sodium bicarbonate—shifts potassium back into cells.
e. Hemodialysis or peritoneal dialysis.
a. Restrict potassium intake.
b. Calcium will counteract negative effects of potassium on the heart.
c. Frequently check cardiac monitor placed on client with hyperkalemia.
d. Penicillin in form of potassium should not be administered to clients with hyperkalemia.
Replacement of lost potassium.
a. Administer oral potassium, monitor IV infusion of potassium.
b. Replace no more than 20 mEq of KCl (potassium chloride) in 1 hour.
a. Observe electrocardiogram (ECG) monitor if possible to observe for cardiac effect of KCl.
b. Give foods rich in potassium—bananas, molasses, oranges, raisins, seafood.
c. Assess for hypokalemia in clients who require frequent NG suctioning.
2. Sodium: Test for deficiency or excess of electrolyte seen in some endocrine disorders and monitor fluid balance in IV electrolyte therapy.
Increased level is a very high concentration of sodium in the extracellular fluid dehydration,severe vomiting or diarrhea, decreased water intake, fever, renal failure, and ingestion of sodium chloride (NaCl).
Decreased level is a very low concentration of sodium in the extracellular fluid diuretics, excessive perspiration, GI loss (vomiting, diarrhea), lack of sodium in diet, Addison’s disease or adrenal insufficiency, burns, and excessive IV solutions without NaCl replacement.
Removal of excess sodium.
a. Administer salt-free IV solutions (dextrose), monitor for hyponatremia, and administer 0.45% NaCl to prevent hyponatremia.
b. Restrict sodium in diet.
c. Discontinue drugs that cause sodium retention.
a. Weigh daily and record intake and output (I&O).
b. Assess blood pressure level in terms of fluid retention.
Replacement of lost sodium.
a. Administer IV fluids with sodium (3% or B 5% saline) monitor venous pressure to prevent circulatory overload.
b. Restrict water intake monitor intake and output.
a. Clients who excrete excess sodium must be advised how to increase sodium intake.
b. Assist client to identify symptoms of sodium depletion.
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