Normal value of serum urea?

Appeared in: PGIMS Rohtak NO - 2017

Explanation

The normal reference range for blood urea is approximately 15-40 mg/dL, as cited in standard biochemistry textbooks.
The option 30-45 mg/dL is the best fit among the choices, as it largely overlaps with the accepted normal range and accounts for variations due to age and different laboratory standards.
Serum urea levels tend to be in the higher end of the normal range for older adults.
This value is distinct from Blood Urea Nitrogen (BUN), which has a lower numerical range (approximately 7-20 mg/dL).

Option A: The range of 5-10 mg/dL is too low for serum urea. This range is more consistent with the normal values for Blood Urea Nitrogen (BUN).
Option C: The range of 35-50 mg/dL is higher than the typical normal range for serum urea (15-40 mg/dL). A value of 50 mg/dL would generally be considered elevated.
Option D: The range of 40-60 mg/dL is clearly elevated and outside the normal reference values for serum urea. These levels would suggest potential renal dysfunction or other underlying issues.

Clinical Relevance

Nursing practice connection: Knowing Normal laboratory values for serum urea helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses must be able to differentiate between serum urea and BUN results to accurately interpret lab reports and assess a patient's renal function and hydration status.
Monitoring trends in serum urea is crucial for patients with kidney disease, heart failure, liver disease, or those on diuretic therapy.
What if? If a patient's lab report shows a BUN of 15 mg/dL, the nurse can calculate the approximate serum urea level (15 x 2.14 ≈ 32 mg/dL), confirming it is within the normal range.

How to Approach the Question

First, identify the specific lab value being asked for: 'serum urea'.
Recall the normal reference range for serum urea in an adult.
Be careful not to confuse the normal range for serum urea with that of Blood Urea Nitrogen (BUN), which is a common point of confusion. Remember that the numerical value for urea is higher than for BUN.
Evaluate the given options to see which one best matches the recalled normal range.
Select the option that represents the most widely accepted range, considering that laboratory reference values can have slight variations.

Concept Tested & Keywords

QPQKs7ALAFdvcw-QU5PV6A

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 2 — Subpart A (pp 1-239 of 478) p. 52-54

E6 textbook of Applied Biochemistry and Nutrition & DieteticsHarbans Lal (pp 26-464 of 479) pp. 183-185, 180-182

Practise the full PGIMS Rohtak NO - 2017

Attempt every question from this paper in a timed mock, then review the full solution for each one.