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MODULE 19: THE URINARY SYSTEM
PART 6 OF 7
Stina’s renal biopsy is read as AA-type amyloid deposited in the glomeruli, staining positive with Congo red and showing apple-green birefringence under polarized light; the report names renal AA amyloidosis — the defining complication of untreated FMF.
Slide 1 Transcript
PATIENT CHART
STINA
THIS PART
Age 51
PRESENTING WITH
Albumin-rich Proteinuria
TESTS ORDERED
Serum EPO, Renal Biopsy, 24-hour urineThe liquid waste excreted by the kidneys. protein
DIAGNOSIS
Renal Amyloid depositionThe process of bone matrix formation by osteoblasts.
CHART CLUES
COLLECTED AS YOU GO
Proteinuria History
Incidental Phlebolith
Albumin-Rich Glomerular Proteinuria
Intact Tubular Function Beside a Glomerular Leak
Neurogenic Bladder Rejoins + the EPO Thread
Biopsy-Confirmed Amyloid in Glomeruli
Renal Amyloid Deposition
Put your money down: What has been physically breaking Stina’s glomerular filter — and can anything actually stop it?
Bet before the biopsy. We’ve localized the leak to the glomerular barrier and shown her tubules are fine. Commit now: what has been infiltrating and wrecking that barrier all these years — and is this an irreversible decline, or something a single faithful daily drug can halt at its root?
Pick the answer you believe now. We’ll come back to it later!
Where the Amyloid Lands
Here is the diagnosis the whole course has been pointing at. For years Stina’s untreated FMF kept her inflammation high, driving her liverA large organ that produces bile, detoxifies blood, and stores nutrients. to overproduce serum amyloid A. SAA is meant to rise and fall with inflammation, but kept high for years its fragments misfold into insoluble fibrils — AA amyloid — that deposit in tissues. The kidney, with its enormous blood flow and delicate glomerular barrier, is the favorite landing site: fibrils accumulate in the glomeruli, battering the basement membrane and podocyte slits until the sieve can no longer hold protein back. A biopsy confirms it — amyloid binds Congo red and glows apple-green under polarizedA resting neuron’s membrane with a more negative charge inside than outside. light.
How Amyloid Lands
A protein that doesn’t clear — it deposits, in the kidney.
Slide 2 Transcript
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Single Choice: Why is the kidney amyloid’s favorite target?
Confirming and Curing
Congo red, apple-green, and the drug that starves it.
Slide 3 Transcript
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Drag the Words: Trace the SAA → amyloid → leak pathway and colchicine’s point of action.
Reading the Leak, Naming the Disease
With the broken barrier in view, two ideas snap into focus. First, the kind of proteinuria tells you where the kidney is failing: glomerular proteinuria — Stina’s kind — is a leak of large proteinsLarge molecules made of amino acids with various functions in the body. like albuminA plasma protein that helps maintain osmotic pressure and transport substances. through a damaged filter, climbing into the heavy nephrotic range with low blood albumin and edemaExcess fluid in interstitial spaces.; tubular proteinuria is a smaller leak of low-molecular-weight proteins the tubule failed to reabsorb. Her heavy, albumin-rich, biopsy-confirmed leak is unmistakably glomerular. This is renal AA amyloidosis, the defining, life-threatening complication of untreated FMF.
Chart Clue #19
Not a trace — an alarm.
Slide 4 Transcript
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Multiple Choice: What does colchicine do that protects Stina’s kidneys?
When a Trace Isn’t Nothing
Context turns noise into signal.
Slide 5 Transcript
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Mark the Words: Mark the history that turns a benign trace into an alarm.
Treatable at the Root
And here is the part that makes this a teaching triumph rather than only a tragedy: it is treatable at its root. Amyloid is fed by SAA, and SAA is fed by inflammation — so colchicine, taken faithfully, suppresses the FMF attacks and lowers SAA, starving the amyloid of its raw material and halting, even partly reversing, its deposition. This is why colchicine adherence is no longer about pain; for Stina it is about whether her kidneys survive. The drug that controlled her attacks is now the drug that protects her life.
Glomerular versus Tubular
The kind of leak names the broken station.
Slide 6 Transcript
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Summary: Pick the statement that correctly distinguishes glomerular from tubular proteinuria.
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Slide 7 Transcript
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FINDING!
Biopsy-Confirmed Renal AA Amyloidosis
Biopsy shows AA amyloid in the glomeruli — Congo red positive, apple-green birefringent — with nephrotic-range, albumin-rich (glomerular) proteinuria. Chart entry: renal AA amyloidosis, the defining complication of untreated FMF, treatable at its root by colchicine lowering SAA.
Confirm or refute your bet: What has been physically breaking Stina’s glomerular filter — and can anything actually stop it?
Now that the biopsy is back, return to the bet. Years of high SAA misfolded into amyloid that physically clogged and broke her glomerular barrier — and it is not hopeless: colchicine, by shutting down the SAA supply, can halt and even partly reverse it. Chart entry: renal AA amyloidosis confirmed, colchicine adherence now a matter of kidney survival.
Slide 7 Transcript
NEXT PART
One line on a lab report set all of this in motion — and was nearly dismissed. With the mechanism in hand, we can finally log the clue and read it for what it always was.
QUICK QUESTIONS
QUICK QUESTIONS
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← Familial Mediterranean Fever — case home
All pages for Module 19 — The Urinary System
19.0 Module Overview
19.1 A Little Protein in the Urine
19.2 The Kidney from the Outside In
19.3 The Nephron and the Glomerular Filtration Barrier
19.4 Reabsorption, Secretion, and How Urine Is Made
19.5 Master Regulator: Blood Volume, Pressure, and the Path of Urine
19.6 When the Filter Breaks
19.7 Not a Trace, an Alarm
19.8 Conclusion and Assessment
19.9 Evidence Behind the Case
All Modules
- Anatomical Language, Membranes & Homeostasis
- Just Enough Chemistry
- The Cell & Its Transport
- Making Cells & Proteins
- The Integumentary System
- The Skeletal System
- The Muscular System
- Nervous Tissue & the Senses
- The Spinal Cord
- The Brain & the Blood–Brain Barrier
- The Autonomic Nervous System
- Special Senses (in developmentThe process of growth and differentiation.)
- The Endocrine System
- Blood
- The Heart
- Blood Vessels
- The Digestive System
- The Respiratory System
- The Urinary System
- Fluids, Electrolytes & Acid–Base Balance
- The Reproductive System
- The Immune System
List of terms
- urine
- deposition
- liver
- polarized
- proteins
- albumin
- edema
- development