Victor A. Leitao

Impact of Long-Term Potassium Citrate Therapy on Urinary Profiles and Recurrent Stone Formation

PURPOSE Potassium citrate therapy has become one of the cornerstones of medical stone management. We elucidated the long-term effects of potassium citrate on urinary metabolic profiles and its impact on stone formation rates. MATERIALS AND METHODS We performed a retrospective cohort study in patients treated at the Comprehensive Kidney Stone Center at our institution between 2000 and 2006. Patients with pre-therapy and post-therapy 24-hour urinary profiles available who remained on potassium citrate for at least 6 months were included in the analysis. RESULTS Of the 1,480 patients with 24-hour urinary profiles 503 met study inclusion criteria. Mean therapy duration was 41 months (range 6 to 168). Overall a significant and durable change in urinary metabolic profiles was noted as soon as 6 months after the onset of therapy. These changes included increased urinary pH (5.90 to 6.46, p <0.0001) and increased urinary citrate (470 to 700 mg a day, p <0.0001). The stone formation rate also significantly decreased after the initiation of potassium citrate from 1.89 to 0.46 stones per year (p <0.0001). There was a 68% remission rate and a 93% decrease in the stone formation rate. CONCLUSIONS Potassium citrate provides a significant alkali and citraturic response during short-term and long-term therapy with the change in urinary metabolic profiles sustained as long as 14 years of treatment. Moreover, long-term potassium citrate significantly decreases the stone formation rate, confirming its usefulness in patients with recurrent nephrolithiasis.

Renal Medullary Carcinoma

Young patients with sickle cell trait or disease present a higher risk for renal medullary carcinoma, an aggressive renal tumor, with dismal prognosis, with a median survival of 4 months from the time of diagnosis. We report a 26-year-old patient with a 2-month history of bone pain at the right iliac crest, loss of weight, recurrent macroscopic hematuria and abdominal mass. Imaging studies demonstrated a 10-cm mass in the right kidney. Pathological evaluation revealed a medullary carcinoma and the patient died after 4 months, despite adjuvant treatment. Whenever a patient with sickle cell trait or disease presents with hematuria and/or flank pain, the possibility of a renal medullary carcinoma should always be kept in mind, with thorough investigation and expeditious treatment.

Stone Forming Risk Factors in Patients With Type Ia Glycogen Storage Disease

PURPOSE Patients with type Ia glycogen storage disease have an increased recurrent nephrolithiasis rate. We identified stone forming risk factors in patients with type Ia glycogen storage disease vs those in stone formers without the disease. MATERIALS AND METHODS Patients with type Ia glycogen storage disease were prospectively enrolled from our metabolic clinic. Patient 24-hour urine parameters were compared to those in age and gender matched stone forming controls. RESULTS We collected 24-hour urine samples from 13 patients with type Ia glycogen storage disease. Average +/- SD age was 27.0 +/- 13.0 years and 6 patients (46%) were male. Compared to age and gender matched hypocitraturic, stone forming controls patients had profound hypocitraturia (urinary citrate 70 vs 344 mg daily, p = 0.009). When comparing creatinine adjusted urinary values, patients had profound hypocitraturia (0.119 vs 0.291 mg/mg creatinine, p = 0.005) and higher oxalate (0.026 vs 0.021 mg/mg creatinine, p = 0.038) vs other stone formers. CONCLUSIONS Patients with type Ia glycogen storage disease have profound hypocitraturia, as evidenced by 24-hour urine collections, even compared to other stone formers. This may be related to a recurrent nephrolithiasis rate greater than in the overall population. These findings may be used to support different treatment modalities, timing and/or doses to prevent urinary lithiasis in patients with type Ia glycogen storage disease.

Comparison of Light Spot Hydrophone (LSHD) and Fiber Optic Probe Hydrophone (FOPH) for Lithotripter Field Characterization

Characterization of the acoustic field of a shock wave lithotripter is important for determining the performance of the device. In this study, we compare the performance of a newly developed Light Spot Hydrophone (LSHD) with the current standard, i.e., the Fiber Optic Probe Hydrophone (FOPH). An electromagnetic (EM) shock wave lithotripter was selected and each hydrophone was used to map the acoustic field of the lithotripter. The peak positive pressure P+, peak negative pressure P−, pulse duration, and effective acoustic energy were calculated using the collected data. Both the LSHD and the FOPH have similar measurement characteristics. They both provide excellent P+ measurement accuracy and response. Although the LSHD was found to provide more repeatable P− pressure measurements, both devices provide excellent pressure measurement of lithotripter shock fields.

In Vitro Comparison between HM‐3 and MODULARIS Lithotripters

Shockwave lithotripsy (SWL) is currently the preferred method of treatment for renal calculi < 10 mm in size. Dornier introduced the electrohydraulic HM‐3 in 1983, which has become the “gold standard” for SWL. Since then other types of lithotripters (electromagnetic and piezoelectric) have been developed. We compared the third‐generation electromagnetic shockwave lithotripter Siemens MODULARIS to the HM‐3 in vitro assessing acoustic measurement and stone comminution in a holder. Similar results were encountered.

URETHRAL CONSTRICTOR - PENOSCROTAL IMPLANTATION

exposed. The area of the cuff implantation must be proximal around the bulbar urethra, in depth. The introduction of the cuff behind the corpus spongiosum must be close the tunica albuginea of corpus cavernosum in order to avoid urethral injury which should stop the procedure. After positionning the right angle, the space is carefully enlarged on 2cm .Then we measure the size of the cuff, here 4 cm. An iliac incision is performed laterally to the rectus muscles. After opening the musculo-aponevrotic plane, creation of an extra-peritoneal space for the pressure regulating balloon. The positionning of the balloon is here different of the technique described by Wilson who places the balloon through the inguinal ring. A 61-70 cmH2O pressure reservoir is chosen. The cuff is placed around the bulbar urethra, in depth. A subcutaneous tunnel is performed for connexion to the reservoir. The different planes are closed with absorbable sutures. Creation of a subcutaneous space in the scrotum to place the pump and it’s closed with absorbable sutures. When all components are in place they are connected. RESULTS: The sphincter is desactivated for 6 weeks. This delayed activation assures no undue tissu trauma during the healing phase. CONCLUSIONS: The penoscrotal approach is an alternative to perineal approach. Position of the patient and the surgical team is simplified. Operative time is decreased. This approach allows an easy dissection and mobilisation of the bulbar urethra. The anus is taked away from the operating area. Complementary studies and informations about long-term results and complications of the penoscrotal approach are necessary to place this technique as an alternative of the perineal approach.

Subcutaneous Marcaine Infiltration and Post‐Operative Pain Perception after Percutaneous Nephrolithotomy

Recent studies have shown a significant decrease in patient reported pain scores when operative incisions are infiltrated with subcutaneous local anesthetic. We hypothesize that patient reported pain and narcotic use could be further decreased for patients with post‐percutaneous nephrolithotomy nephrostomy tubes if the nephrostomy tract and incision are infiltrated with local anesthetic.

Does Potassium Citrate Medical Therapy Increase the Risk of Calcium Phosphate Stone Formation

Potassium citrate has been extensively used in the treatment of recurrent nephrolithiasis. Recent evidence suggests that it may contribute to increasing urinary pH and, as such, increase the risk of calcium phosphate stone formation. We performed a retrospective review of our patients to further investigate this phenomenon.