Kidney stones

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Kidney stones

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A 45-year-old woman comes to the outpatient clinic because of intermittent left flank pain that has been ongoing for the past two weeks. She has noticed blood in her urine on a few occasions. Moreover, the pain has become more severe. She works as a personal trainer. Family and medical history are unremarkable. Temperature is 39.0°C (102.2°F), pulse is 80/minute, respiratory rate is 16/minute, and blood pressure is 130/95 mm Hg. An x-ray is ordered and shown below:

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Which of the following best describes the composition of this pathological structure?

External References

First Aid

2024

2023

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2021

Allopurinol

kidney stones p. 622

Ammonium magnesium phosphate (kidney stones) p. 622

Arginine

kidney stones and p. 622

Calcium (kidney stones) p. 622

Calcium oxalate nephrolithiasis p. 67

Cystine (kidney stones) p. 622

Gout p. 473

kidney stones and p. 622

Hematuria p. 614

kidney stones p. 620

Hydronephrosis p. 617

kidney stones p. 622

Hyperuricemia

kidney stones and p. 622

Kidney stones p. 620

Crohn disease association p. 389

electrolyte disturbances p. 609

hematuria with p. 612

horseshoe kidney and p. 597

hydronephrosis p. 617

hyperparathyroidism p. 342

postrenal azotemia p. 620

risk factors for p. 611

UTIs p. 179

Klebsiella spp. p. 143

kidney stones p. 622

Lysine

kidney stones p. 622

Nephrolithiasis p. 618

calcium oxalate p. 67

Ornithine

kidney stones and p. 622

Proteus mirabilis

kidney stones p. 622

Pyelonephritis p. 619

kidney stones p. 622

Staghorn calculi p. 622

Staphylococcus saprophyticus p. , 134

kidney stones p. 622

“Stone bone p. 467

Uric acid (kidney stones) p. 622

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With nephrolithiasis, “nephro-” refers to the kidneys, and “-lithiasis” means stone, so nephrolithiasis means kidney stones, sometimes also referred to as renal calculi or urolithiasis.

Kidney stones form when solutes in the urine precipitate out and crystalize, and although these most commonly form in the kidneys themselves, they can also form in the ureters, the bladder, or the urethra.

Now, urine’s a combination of water, which acts as a solvent, and all sorts of particles, or solutes.

In general, when certain solutes become too concentrated in the solvent, they become supersaturated.

Urinary supersaturation of certain solutes results in precipitation out of the solution and formation of crystals.

Those crystals then act as a nidus, or place where more solutes can deposit and over time it builds up a crystalline structure.

This can happen if there’s an increase in the solute, or a decrease in the solvent, as would be the case with dehydration.

In addition, there are substances like magnesium and citrate that inhibit crystal growth and aggregation, preventing kidney stones from forming in the first place.

In the majority of cases, the inorganic precipitate is calcium oxalate, formed by a positively charged calcium ion binding to a negatively charged oxalate ion, which results in a black or dark brown colored stone that is radio-opaque on an Xray, meaning that it shows up as a white spot.

Sometimes, instead of oxalate, the calcium binds a negatively charged phosphate group to form calcium phosphate stones which are dirty white in color and also radiopaque on an X-ray.

Calcium oxalate crystals are more likely to form in acidic urine, whereas calcium phosphate crystals are more likely to form in alkaline urine.

The exact reason why these stones form is usually unknown, but there are some known risk factors like hypercalcemia and hypercalciuria, having too much calcium in the blood and urine, respectively.

Hypercalcemia can result from increased calcium absorption in the gastrointestinal tract as well as hormonal causes like primary hyperparathyroidism.

Sources

  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Prospective Study of Beverage Use and the Risk of Kidney Stones" American Journal of Epidemiology (1996)
  6. "HELICAL CT OF URINARY TRACT STONES" Radiologic Clinics of North America (1999)
  7. "Diagnosis and Management of Acute Ureterolithiasis" American Journal of Roentgenology (2000)
  8. "Kidney stone disease" Journal of Clinical Investigation (2005)
  9. "An Update and Practical Guide to Renal Stone Management" Nephron Clinical Practice (2010)
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