Recurrent Soft Tissue Infections Associated With Burosumab Therapy in X-Linked Hypophosphatemic Rickets.

X-linked hypophosphatemic rickets (XLH) is a genetic disorder characterized by elevated fibroblast growth factor 23 (FGF23), resulting in renal phosphate wasting and inadequate bone mineralization. Burosumab, a monoclonal antibody that inhibits FGF23 activity, has shown promise in improving renal phosphate reabsorption and clinical outcomes in XLH patients. However, the potential side effects of burosumab, particularly its impact on immune function and susceptibility to infections, remain a subject of concern. In this case report, we describe a 57-year-old male individual with XLH who experienced recurrent soft tissue infections while receiving burosumab therapy. The infections included an olecranon abscess, a cervical retropharyngeal phlegmon with a sternocleidomastoid abscess, and suprapubic cellulitis, all of which were treated with antibiotic therapy. Following discontinuation of burosumab therapy, the patient did not experience further soft tissue infections. These observations suggest a potential association between burosumab therapy and an increased risk of soft tissue infections. Mechanistically, disruption of the FGF23-Klotho signaling axis may lead to impaired humoral immunity mediated by B lymphocytes and compromised innate immune response mediated by macrophages. Further investigation is warranted to better understand the immunological effects of burosumab and its implications for infectious complications in XLH patients.

Zoster Sine Herpete: Confirmatory Diagnosis Using Varicella-Zoster Virus DNA Polymerase Chain Reaction Analysis of Intact Skin Scrapings.

Zoster, commonly known as shingles, is a syndrome caused by the reactivation of the varicella-zoster virus (VZV) that results in characteristic vesicular eruptions in a unilateral dermatomal distribution. Timely diagnosis of zoster sine herpete (ZSH), a variant of shingles without the typical vesicular rash, can be challenging due to the absence of visual cues and limited application of traditional diagnostic methods. Recent case reports have demonstrated the utility of VZV DNA polymerase chain reaction (PCR) analysis of involved skin exudates for confirming ZSH. This report presents a case of acute ZSH involving the left trigeminal nerve, where the diagnosis was confirmed using VZV DNA PCR analysis of skin scrapings. The patient initially presented with radicular pain and was treated for presumed shingles, but persistent neuropathic pain persisted. The confirmatory VZV DNA PCR analysis of the involved skin scraping sample aided in establishing the diagnosis of ZSH. The case highlights the potential of using intact skin scrapings for VZV DNA PCR in confirming ZSH. Prompt initiation of antiviral therapy is crucial for minimizing the duration and severity of radicular pain in ZSH cases. Larger studies are needed to further evaluate the utility of VZV DNA PCR analysis for accurately diagnosing ZSH.

Severe Ketamine-Induced Uropathy Associated With Cholangiopathy Requiring Percutaneous Nephrostomy.

Ketamine-induced uropathy (KIU) is becoming more prevalent as ketamine abuse becomes widespread. Recently, a plethora of reports have highlighted the association between recreational ketamine abuse and its deleterious effects including uropathy and cholangiopathy. However, there are hardly any reports that demonstrate the management of severe KIU in young people. We report a case of an Asian female in her late 20's with a 10-year history of ketamine abuse who presented to the emergency department with sharp, epigastric pain for two weeks. An evaluation revealed acute kidney injury and transaminitis with bilirubinemia. CT scan showed bladder and ureteral wall thickening with hydroureteronephrosis. The patient underwent percutaneous bilateral nephrostomy tubes placement, improving urine output and with acute kidney injury resolution. Repeat renal/bladder US showed near complete resolution of bilateral hydronephrosis. This case documents one of the first few documented cases of severe ketamine-induced uropathy with cholangiopathy necessitating bilateral nephrostomies in the continental U.S.

Thyrotoxic Periodic Paralysis: The Peril of Potassium Replacement.

Hypokalemic periodic paralysis (HPP) is a clinical condition of sudden-onset, recurrent transient episodes of weakness caused by severe hypokalemia. Thyrotoxic periodic paralysis (TPP) is a specific subgroup of the HPP spectrum, where hypokalemia occurs in the setting of thyrotoxicosis, and the repletion of potassium must be performed with caution. A male in his second decade of life with hyperthyroidism non-adherent to methimazole presented with acute-onset bilateral lower extremity weakness. On physical examination, the patient had diffuse thyromegaly and tremors on outstretched hands. Bilateral lower extremity weakness and decreased reflexes were also noted, with preserved muscle tone and normal passive range of motion. Labs demonstrated hyperactive thyroid function and severe hypokalemia at 1.7 mEq/L, with U waves present on the electrocardiogram. In the intensive care unit, the patient received methimazole and propranolol for thyrotoxicosis and a total dose of 60 mEq/L of potassium replacement therapy. Despite the expected correction by 0.6 mEq/L, his follow-up potassium level dramatically increased to 5.7 mEq/L, resulting in the actual correction of 4.0 mEq/L. Within a few hours, the patient regained his baseline strength with a significant improvement in tremors. Patients with TPP present with acute-onset extremity weakness and severe hypokalemia, which reverses quickly with potassium repletion. Clinicians should not only treat thyrotoxicosis but also avoid overly aggressive repletion of potassium as this may lead to rebound hyperkalemia when the initial transcellular potassium shift is reversed.