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Urolithiasis
Published in Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed, MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
Thomas Johnston, James Armitage, Oliver Wiseman
It is hydroxyl (OH−) ions that are responsible for the alkalinisation of urine which is of fundamental significance to the pathophysiology of struvite stone formation. The presence of ammonia in alkaline urine (pH > 7.2) leads to the precipitation of magnesium ammonium phosphate (struvite) crystals which can lead to staghorn stone formation. Specific therapeutic measures for struvite stones therefore include urinary acidification, use of short-term and long-term antibiotics, and the use of urease inhibitors such as acetohydroxamic acid. Percutaneous chemolysis may be combined with ESWL for selective patients with staghorn stones who are not fit for percutaneous nephrolithotomy (Figure 16.2).
Kidneys and ureters
Published in Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie, Bailey & Love's Short Practice of Surgery, 2018
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie
Stone composition: struvite stones need to be completely removed because of associated infection. As previously mentioned, some stones with a very hard composition are difficult to fragment using ESWL, including calcium oxalate monohydrate and cystine stones.
Multiple choice questions (MCQs)
Published in Tristan Barrett, Nadeem Shaida, Ashley Shaw, Adrian K. Dixon, Radiology for Undergraduate Finals and Foundation Years, 2018
Tristan Barrett, Nadeem Shaida, Ashley Shaw, Adrian K. Dixon
Between 70–80% of calculi contain calcium and are radio-opaque. Pure urate (5–10% of all calculi) and xanthine (rare) calculi are radiolucent as are calculi composed of matrix (rare calculi containing mucopolysaccharides or mucoproteins). Struvite (mixed stones) are typically associated with infection, particularly proteus and are usually radio-opaque.
Established and recent developments in the pharmacological management of urolithiasis: an overview of the current treatment armamentarium
Published in Expert Opinion on Pharmacotherapy, 2020
Mohamed Abou Chakra, Athanasios E. Dellis, Athanasios G. Papatsoris, Mohamad Moussa
A guideline from the American Urological Association recommends that patients with residual or recurrent struvite stones may be offered treatment with acetohydroxamic acid (AHA), but only after surgical options have been exhausted [134]. AHA a urease inhibitor therapy is the drug of choice in this scenario, based on three randomized controlled trials demonstrating decreases in stone growth. However, it does not decrease the existing stone burden [135–137]. Withdrawals and adverse events such as tremor, palpitations, headache, anemia, gastrointestinal discomfort, and thromboembolic events were common and statistically significantly more frequent with AHA. The presence of renal insufficiency increases the risk of its toxicity. Thus, AHA is contraindicated for patients with a creatinine level greater than 2.5 mg/dL.
Management of staghorn renal stones
Published in Renal Failure, 2018
Although kidney stones are commoner in men, staghorn stones are less often reported in men compared to women and they are usually unilateral [4–8]. Staghorn stones are infection stones in 49–68% of cases and, therefore, the term staghorn traditionally referred to struvite stone [9,10]. Struvite stone, first described by a Swedish geologist named Ulex in 1845, is composed of magnesium, ammonium, and phosphate and it is closely related to urinary tract infection caused by urease-producing organisms, namely Proteus, Klebsiella, Pseudomonas, and Staphylococcus bacteria [1,11].
Kidney stone compositions and frequencies in a Norwegian population
Published in Scandinavian Journal of Urology, 2019
Gunnhild Kravdal, Dan Helgø, Morten K. Moe
Struvite was found in 5.7% of all stones, with a 3.5-times higher frequency in females. Female struvite stone-formers were older compared to the entire female stone patient group (mean age (63.8 vs 52.6 years) and all were older than 18 years. In contrast, several male struvite formers were younger than 18 years. Nearly all struvite stones also contained CA and less often also CaOx, protein and ammonium hydrogen urate (AmU).