Creatinuria is not produced by?

HPSSC Staff Nurse - 2021

Applied Physiology

Medium

Appeared in: HPSSC Staff Nurse - 2021

Explanation

Healthy adult males have stable, mature muscle mass that efficiently takes up and converts creatine to its waste product, creatinine.
In healthy males, the renal tubules reabsorb virtually all filtered creatine, leading to negligible amounts in the urine.
The presence of creatinuria in an adult male is typically considered a pathological sign, suggesting conditions like muscle wasting diseases, rather than a normal physiological state.

Option A: Children exhibit physiological creatinuria. Their muscle mass is still developing, and their capacity to store creatine is lower than in adults, leading to its excretion in urine.
Option B: Pregnant women commonly have physiological creatinuria. This is attributed to hormonal changes and an increased glomerular filtration rate (GFR) during pregnancy.
Option C: Fasting or starvation leads to creatinuria. The body breaks down muscle protein for energy (catabolism), which releases creatine into the blood and subsequently into the urine.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiological and pathological causes of creatinuria as background academic context rather than a clinical decision trigger.
Understanding the difference between physiological and pathological creatinuria is crucial for nurses when interpreting urinalysis results.
While creatinine levels are a standard measure of kidney function, an unexpected finding of creatinuria in an adult male patient should prompt further investigation for underlying muscle disorders (e.g., muscular dystrophy) or metabolic issues (e.g., hyperthyroidism).
Patient education is important. A nurse may need to explain to a pregnant patient that finding some creatine in her urine is a normal part of pregnancy and not a sign of kidney disease.

How to Approach the Question

First, identify the core concept: The question asks about 'creatinuria', which is the presence of creatine in urine.
Note the negative keyword 'not'. This means you are looking for the group in which creatinuria is an abnormal or absent finding.
Recall or deduce the basic metabolism of creatine. It's used by muscles, and its waste product is creatinine. Creatine itself shouldn't be in the urine of healthy adults in large amounts.
Evaluate each option: Consider the physiological state of each group. Children are growing, pregnant women have altered physiology, and fasting induces muscle breakdown. These are all states of metabolic stress or change.
Contrast these with a 'healthy male', who represents a stable, baseline metabolic state with mature muscle mass.
Conclude that the stable state (healthy male) is the one least likely to have creatinuria, making it the correct answer to the 'not' question.

Concept Tested & Keywords

Concept Tested: Physiological and pathological causes of creatinuria.
Stem keywords: Creatinuria, produced by
Lead-in keywords: not
Negative lead-in flag: The question asks for the condition where creatinuria is NOT present.

Q9GupsGBMzRPMyimLSlTqW

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 2 — Subpart A (pp 1-239 of 478) p. 50-52

E6 Biochemistry U Satyanarayana— Part 1 (pp 26-420 of 840) p. 341-343