Differential diagnosis:

- Nephrolithiasis may be part of a more generalized calcification of the kidney termed nephrocalcinosis. It may be part of multisystem disorders and congenital abnormalities of the kidney or urinary tract (CAKUT). Nephrolithiasis may be a complicating feature of autosomal dominant polycystic kidney disease and medullary sponge kidney due to architectural and metabolic abnormalities associated with these conditions.

Renal calculi are

Kidney stones (renal calculi) are accumulations of crystals that are condensed from the urine. When the stone moves into the ureter, the stone may serve as a dam and prevent or partially prevent the flow of urine.

The kidney continues to produce urine, which backs up behind the stone and may cause the kidney to swell.
The pressure buildup causes much of the pain associated with kidney stones.
However, the pressure also helps to push the stone along until it enters the bladder.
Depending on the level of the location of the stone, which will vary as pressure moves it along, pain will most likely be referred from the lumbar region or to the hypogastric region to the groin.
The pain is referred to the cutaneous areas supplied by the same spinal cord segments that supply the ureter (i.e., lesser splanchnic, T10–T11; least splanchnic, T12; lumbar splanchnic nerves, L1–L2). The urethra has a larger lumen than the ureter, and therefore, the symptoms are usually relieved at this point.

Work up for hyperparathyroidism

stone (calculus) formation within the renal tract.

1. Pain control: Hydromorphone

2. Urologic intervention should be postponed unless

a. there is evidence of UTI,

b. a low probability of spontaneous stone passage (e.g., a stone measuring ≥6 mm or an anatomic abnormality),

c. or intractable pain.

Distinguish between calcium-containing and noncalcium-containing stones (eg, urate, cystine).

This will determine the best imaging modality for diagnosis and follow-up.

[A ureteral stent may be placed cystoscopically, but this procedure typically requires general anesthesia, and the stent can be quite uncomfortable, may cause gross hematuria, and may increase the risk of UTI.]

If an intervention is indicated, the selection of the most appropriate intervention is determined by the size, location, and composition of the stone; the urinary tract anatomy; and the experience of the urologist.

Extracorporeal shockwave lithotripsy, the least invasive option, uses shock waves generated outside the body to fragment the stone.

An endourologic approach can remove a stone by basket extraction or laser fragmentation. For large upper-tract stones, percutaneous nephrostolithotomy has the highest likelihood of rendering the patient stone-free.

Advances in urologic approaches and instruments have nearly eliminated the need for open surgical procedures such as ureterolithotomy or pyelolithotomy.

A 24-year-old female is hospitalized with a kidney stone and pyelonephritis. She is started on appropriate intravenous antibiotics and fluid therapy. She has no allergies and has never had opioids in the past. Her weight is 48 kg. Her colicky pain is rated at 7 to 8 out of 10 in severity at admission, with significant nausea and occasional vomiting. She has not passed the stone. What is/are reasonable analgesic option(s)?

Fentanyl transdermal 12 μg/h patch every 3 days

Acetaminophen 1000 mg orally every 8 hours as needed

Naloxone 0.4 mg IV every 8 hours as needed

Hydromorphone 0.6 mg IV every 3 hours as needed

The correct answer is D.

Explanation:

Transdermal fentanyl should be used only with opioid-tolerant patients with moderate to severe chronic pain requiring continuous analgesic dosing. Acetaminophen is likely not potent enough to control this moderate to severe pain, and may not be absorbed well orally due to the potential for vomiting. Naloxone is used to reverse the effects of opioids. Hydromorphone at this dose is appropriate for an opioid-naive patient.

Nephrolithiasis

USMLE Reviewer

Diseases and Disorders