| Course | PA 524 Comprehensive Clinical Module Nephrology & Genitourinary |
|---|---|
| Week | 2 |
| Paper type | Filtration estimate write-up |
| Length | About 730 words, 5 pages |
| Format | APA 7 student paper |
| School | Chamberlain University |
| Program | Master of Physician Assistant Studies (MPAS) |
| Updated | October 2026 |
Free sample paper for PA 524 Week 2
Filtration Estimate Write-Up: The 2021 CKD-EPI Creatinine Equation Gives G.H. 53 mL/min/1.73 m2, About 51 mL/min Unindexed and a Cockcroft-Gault Clearance of 38, With Each Input Questioned
Student Name
Chamberlain University
PA 524: Comprehensive Clinical Module Nephrology & Genitourinary
Instructor Name
Month Day, Year
Filtration Estimate Write-Up: The 2021 CKD-EPI Creatinine Equation Gives G.H. 53 mL/min/1.73 m2, About 51 mL/min Unindexed and a Cockcroft-Gault Clearance of 38, With Each Input Questioned
Naming the Formula First
The estimate uses the 2021 CKD-EPI creatinine equation, which removed the race term from earlier versions and is now the recommended equation in the United States (Inker et al., 2021). For a male patient with a serum creatinine above 0.9 mg/dL, the equation is 142 multiplied by the ratio of creatinine to 0.9 raised to the power minus 1.200, multiplied by 0.9938 raised to the power of age.
Inputs as the Case Gives Them
Serum creatinine: 1.4 mg/dL, drawn at a routine clinic visit, standardized assay. Earlier values: 1.3 and 1.4 over the past year, so the level is stable.
Age: 74 years.
Sex: male.
Weight: 58 kg. Height: 170 cm.
The Substitution
Creatinine divided by 0.9: 1.4 divided by 0.9 equals 1.556.
1.556 raised to minus 1.200: about 0.588.
0.9938 raised to the 74th power: about 0.631.
142 multiplied by 0.588 multiplied by 0.631: about 52.7.
Result: eGFR about 53 mL/min/1.73 m2.
Indexed or Not
This figure is scaled as though G.H. had the reference body size of 1.73 m2. G.H.'s body surface area, by the Mosteller formula, is the square root of 170 multiplied by 58 divided by 3,600, or about 1.66 m2. The unindexed filtration rate is 53 multiplied by 1.66 divided by 1.73, about 51 mL/min. For staging chronic kidney disease, the indexed value is used. For dosing a drug, the unindexed value is the more relevant one, since the drug is cleared by G.H.'s actual kidneys, not a standardized pair (Stevens et al., 2024).
The Dosing Estimate Beside It
Many drug labels were written using the Cockcroft-Gault creatinine clearance. For G.H. the numerator is 140 less 74, or 66, times 58 kg, giving 3,828; the denominator is 72 times 1.4, or 100.8; the quotient is about 38 mL/min. The gap between 51 and 38 matters when a drug's label changes dose at a clearance of 50.
Interrogating Each Input
Creatinine: stable over a year, so steady state holds. But G.H. has a below-knee amputation and low muscle mass, which lowers creatinine production, so all three figures probably overstate filtration.
Age: entered exactly; the equation's age term is reliable.
Sex: entered as recorded; the equation's sex term assumes typical muscle mass for sex, which G.H. does not have.
Weight in Cockcroft-Gault: actual weight was used, since G.H. is not obese; with obesity, an adjusted weight would be considered.
The Scope Paragraph
This estimate supports staging: an indexed filtration rate of 45 to 59 places G.H. in category G3a, subject to confirming that it has lasted more than three months and to measuring urine albumin. It does not support fine dosing for a drug with a narrow margin, because the muscle loss makes every creatinine-based figure uncertain. The guideline suggests measuring cystatin C when the creatinine-based estimate is thought to be inaccurate, and using the combined creatinine and cystatin C equation (Stevens et al., 2024). That test has been ordered.
What Cystatin C Would Change
If cystatin C comes back near 1.0 mg/L, the combined equation would place G.H.'s filtration lower than the creatinine estimate, consistent with the muscle loss, and the gabapentin and any future antibiotic doses would be chosen against that lower figure. If cystatin C is high for reasons unrelated to the kidney, such as thyroid disease or steroid use, neither is present here, the combined estimate would be checked against a measured clearance before any narrow-margin drug is started. The decision to order it rests on the guideline's advice for patients in whom creatinine is known to mislead.
How the Result Is Reported
In the chart: eGFR 53 mL/min/1.73 m2 by the 2021 CKD-EPI creatinine equation; likely overestimate because of low muscle mass after amputation; cystatin C pending. In the medication review: creatinine clearance about 38 mL/min by Cockcroft-Gault, actual weight. Writing the equation and the caveat beside the number prevents the next reader from treating it as a measured value.
References
Inker, L. A., Eneanya, N. D., Coresh, J., Tighiouart, H., Wang, D., Sang, Y., Crews, D. C., Doria, A., Estrella, M. M., Froissart, M., Grams, M. E., Greene, T., Grubb, A., Gudnason, V., Gutierrez, O. M., Kalil, R., Karger, A. B., Mauer, M., Navis, G., . . . Levey, A. S. (2021). New creatinine- and cystatin C-based equations to estimate GFR without race. New England Journal of Medicine, 385(19), 1737-1749. https://doi.org/10.1056/NEJMoa2102953
Stevens, P. E., Ahmed, S. B., Carrero, J. J., Foster, B., Francis, A., Hall, R. K., Herrington, W. G., Hill, G., Inker, L. A., Kazancıoğlu, R., Lamb, E., Lin, P., Madero, M., McIntyre, N., Morrow, K., Roberts, G., Sabanayagam, D., Schaeffner, E., Shlipak, M., . . . Levin, A. (2024). KDIGO 2024 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney International, 105(4, Suppl.), S117-S314. https://doi.org/10.1016/j.kint.2023.10.018
PA 524 Week 2 instructions, in plain terms
Week two asks for a written estimate of kidney filtration. Name the formula first, with its version, and explain why it is the one used. List the inputs exactly as the case supplies them, including evidence that the creatinine is stable. Show the substitution in a single block that a reader can check line by line, with units on the result. Say whether the result is indexed to standard body size, and give the unindexed figure if a later decision, such as drug dosing, needs it. If drug labels for your patient use a different estimate, calculate it beside the first. Then question each input: is it reliable for this person? Close with a scope paragraph stating what the estimate supports and what it does not. Cite the guideline and the equation's source.
Inside the PA 524 Week 2 example
The paper names the 2021 CKD-EPI creatinine equation and cites Inker and colleagues on the removal of the race term. Inputs are listed: creatinine 1.4 and stable over a year, age 74, male, 58 kg and 170 cm. The substitution runs in four lines to about 52.7. A section converts the result using a Mosteller body surface area of 1.66 m2 to about 51 mL/min and explains when each form applies, citing KDIGO 2024. The Cockcroft-Gault calculation gives about 38 mL/min and explains the gap at a dosing threshold of 50. Each input is questioned, with muscle loss flagged as making all figures overstate filtration. The scope paragraph assigns G3a pending confirmation and albumin, orders cystatin C, explains what it would change and gives the chart wording with its caveat.
Reading the PA 524 Week 2 grading rubric
The rubric on this write-up rewards a checkable calculation. A result given without the formula's name, the inputs or the substitution loses the most because nothing can be verified. Faculty next check units and indexing; failing to say whether a figure is indexed, or using an indexed figure to dose a drug without comment, costs significant marks. Credit goes to questioning each input rather than assuming the equation fits the patient. A Cockcroft-Gault estimate earns marks when drug decisions are in view and its difference from the eGFR is explained. The scope paragraph is graded on stating clear limits and an appropriate confirmatory test. Arithmetic errors are deducted even when the conclusion is right. The equation's source and current guidance should be cited.
Common PA 524 Week 2 mistakes, and how to avoid them
The common mistake in this assignment is reporting the laboratory's eGFR without showing where it came from or whether it fits the patient. Send your case inputs and the purpose of the estimate, and the write-up drafted for you would name the formula, list your inputs, run the substitution step by step and state the units and indexing. If drugs are involved, a clearance estimate is added beside it with the difference explained. Each input is questioned against your patient's build, diet and medicines. The scope paragraph says what the number can support and which confirmatory test would help. If your course uses another equation, the sample follows it. Recalculate every line yourself from your own case values before relying on the figures.
Get a PA-524 Week 2 example written to your instructions
Send the assignment sheet with the formula your section teaches named on it, plus any worked model the classroom posted, and a custom example is built on that formula and returned inside 24 to 48 hours, the first one free. Where the case values are yours to invent, a consistent set is constructed so the case holds together without belonging to anybody.
More PA 524 papers and MPAS samples
- PA 524 Week 1: Filtration Stand-In Discussion Post
- PA 524 Week 3: Urinalysis Interpretation
- PA 524 Week 4: Prerenal Versus Intrinsic Brief
- PA 524 Week 5: Volume and Sodium Case
- PA 524 Week 6: Acid-base Disorder Set
- PA 524 Week 7: Urinary Obstruction Brief
- PA 524 Week 8: Renal Dosing Adjustment Table
- PA 522 Week 2: Feedback Axis Explainer
- PA 520 Week 2: Spirometry Interpretation
- PA 518 Week 2: ECG Interpretation Drill
- PA 516 Week 2: Tympanic Membrane Documentation
PA 524 Week 2 questions, answered
Our case gives no weight. Can the example still produce a number?
Yes, and how it handles the absence is the interesting part. A formula that needs a weight gets one clearly labeled as assumed, with the assumption stated in the text and the effect of being wrong about it described in a line. A formula that does not need a weight is preferred where the section allows a choice, and the write-up says why it was chosen.
How much arithmetic should be visible?
Enough that a marker can land on the step that went wrong without recomputing anything, which usually means the substituted line and the result, not a page of algebra. The reasoning marks are elsewhere, so a submission stuffed with intermediate figures and thin on interpretation reads as effort in the wrong place. Sections that supply a calculation sheet want it followed exactly.
Does the write-up have to assign a stage?
Only where the assignment asks for one, and then it is stated as a category with the figure that produced it sitting beside. A stage offered in place of the rate answers a question nobody put, and a stage attached to a value that has been climbing since admission claims a stability the case has not shown. If your sheet wants both, they both appear.
Where can I find a free PA 524 Week 2 sample paper?
This page carries the complete PA 524 Week 2 filtration estimate, with the CKD-EPI 2021 substitution shown line by line, an unindexed figure and a Cockcroft-Gault clearance.
Why does the PA 524 Week 2 sample give an unindexed figure?
Drug dosing depends on the patient's actual kidneys rather than a standard 1.73 m2 body, so the indexed value is converted using body surface area.