Development of osteomalacia in a post-liver transplant patient receiving adefovir dipivoxil

Osteomalacia and renal failure due to Fanconi syndrome caused by long-term low-dose Adefovir Dipivoxil: a case report

Background

Progressive bone pain and fracture and abnormal positron emission tomography combined with a computed tomography are main reasons for the oncologists suspecting bone tumor. During the patient’s medical treatment, the oncologists’ unfamiliarity with adverse reactions to anti-HBV drugs were main reason for the long-term exposure to the drug and the adverse reaction (ADR) experienced by the patient.

Case presentation

A 63-year-old Chinese man had a 27-month history of progressive generalized bone pain combined with spontaneous fractures. Positron emission tomography combined with a computed tomography, revealed an abnormal increase in ribose metabolism and low positron serum inorganic phosphorus concentration (0.7; 0.78–1.65 mmol/L). Serum creatinine level was 252 μmol/L (53–97) μmol/L, and glomerular filtration rate was 22.79 mL/min/1.73 m². The patient was referred to a multidisciplinary clinic to clarify the diagnosis of myeloma or bone tumor for further treatment in 2017. His medical history revealed that he had a 30-year history of chronic hepatitis B infection. He had received lamivudine at a daily dose of 100 mg for 19 years (1990 to 2009), which had been changed to adefovir (10 mg/day) owing to lamivudine resistance in 2009. Based on the changes in the patient’s laboratory markers and the results of emission computed tomography and other radiographic findings, adefovir-induced hypophosphatemic osteomalacia due to acquired renal Fanconi syndrome was suspected by the clinical pharmacist. Considerable clinical improvement was observed after adefovir discontinuation and the administration of entecavir (1.0 mg, every other day).

Conclusion

Fanconi syndrome with osteomalacia can develop in patients with chronic hepatitis B infection being treated with adefovir at a conventional low dosage of 10 mg/day. This case highlights the importance of ADR as a differential diagnosis and the need of pharmacists with drug safety expertise expert in the patient management.

Nucleos(t)ide analogues for the prevention of hepatitis B recurrence after liver transplantation do not affect serum phosphorus levels

BACKGROUND

Nucleos(t)ide analogues (NAs) constitute the backbone of treatment for the prevention of hepatitis B virus recurrence after liver transplantation (LT). Decline in serum phosphorus levels is a common side effect of nucleotide therapy. Our aim was to assess the impact of nucleotide treatment on the occurrence of hypophosphatemia after LT and determine possible predictors.

METHODS

We retrospectively analyzed data from liver transplant recipients who had been transplanted for various indications. All patients were evaluated every 3 months. Each patient was considered to be having hypophosphatemia when at least one value of serum phosphorus ≤2.5 mg/dL was detected.

RESULTS

In total, 109 patients [83 males (76%)] with a mean age of 55±10 years were included. 46/67 (67%) patients with hepatitis B received a nucleotide. The rate of hypophosphatemia (55%) was not different between patients with hepatitis B and those transplanted for other indications (62%). Patients receiving a nucleotide did not run a greater risk of hypophosphatemia than patients receiving only nucleosides (59% vs. 48%, P=0.39). Male gender and everolimus use were associated with the occurrence of hypophosphatemia in patients with hepatitis B. In multivariate analysis only gender was associated with hypophosphatemia (odds ratio 11.43, 95%CI -2.11 to -0.49; P=0.0025).

CONCLUSIONS

Hypophosphatemia occurs in more than half of liver transplant recipients regardless of the indication for LT. Male gender and everolimus use seem to predispose to hypophosphatemia, whereas the type of antiviral agent does not.

Urinary β-2 Microglobulin Levels Sensitively Altered in an Osteomalacia Patient Receiving Add-on Adefovir Dipivoxil Therapy for Hepatitis B Virus Infection

Adefovir dipivoxil (ADV) is effective for hepatitis B virus (HBV) infection; however, ADV may provoke renal injury resulting in osteomalacia, and this side effect is seldom recognized until bone fractures emerge. We herein present a 66-year-old woman with HBV infection who received ADV for 6 years. Although she exhibited no sign of bone fractures, her urinary β-2 microglobulin (β2MG) level increased to 83,837 μg/L and scintigraphy revealed minimal fractures of the third rib. ADV was subsequently reduced and her urinary β2MG rapidly fell to 3,637 μg/L. Conversely, her urinary N-acetyl-β-D-glucosaminidase, and serum phosphate, alkaline phosphatase levels did not respond.

Adefovir- or Lamivudine-Induced Renal Tubular Dysfunction after Liver Transplantation

To reduce hepatitis B virus reinfection after liver transplantation (LT), patients often receive antihepatitis B immunoglobulin (HBIG) alone or combined with antiviral nucleoside/nucleotide analogs (NUCs); however, proximal renal tubular dysfunction (RTD) that was induced by NUCs in liver recipients was rarely reported. Here, we analyzed RTD and renal impairment (RI) following adefovir (ADV) and lamivudine (LAM) treatment in liver recipients. We retrospectively reviewed medical records of patients treated with HBIG alone (group 1, n = 42) or combined with ADV or LAM (group 2, n = 21) after LT. We compared RTD and RI incidence during the 12 months after LT. An RTD diagnosis required manifestation of at least 3 of the following features: hypophosphatemia, RI, hypouricemia, proteinuria, or glucosuria. No significant differences were observed regarding sex, age, donor type, model of end-stage liver score, and estimated glomerular filtration rate at pre-LT between the 2 groups. Hepatitis B virus recurrence within 12 months was 4.8% in both groups (P = 1.000); however, the RTD incidence was 0% in group 1 and 19.0% in group 2 (P = 0.010). RI occurrence did not differ between the groups. The only risk factor for RI was HBIG administration combined with both LAM and ADV (odds ratio 11.27, 95% confidence interval 1.13-112.07, P = 0.039, vs HBIG alone). RTD occurred more frequently in patients treated with HBIG combined with LAM or ADV compared with HBIG alone. Thus, LAM or ADV therapy can induce RTD after LT, and when administered, liver recipients should be monitored.

Fanconi syndrome due to prolonged use of low-dose adefovir

Fanconi syndrome results from a generalized abnormality of the proximal tubules of the kidney and owing to phosphate depletion can cause hypophosphatemic osteomalacia. Adefovir dipivoxyl (ADV) effectively suppresses hepatitis B virus replication but exhibits nephrotoxicity when administered at a low dosage. We report two cases of Fanconi syndrome induced by ADV at 10 mg/day to call for regular screening for evidence of proximal tubular dysfunction and detailed bone metabolic investigations for prompt detection of ADV nephrotoxicity is critically important to ensure timely drug withdrawal before the development of irreversible tubulointerstitial injury.

Adefovir-induced Fanconi syndrome: diagnostic pearls and perils of late or missed diagnosis

Low-dose adefovir therapy has been increasingly recognised as a cause of Fanconi syndrome. Being relatively novel, early diagnosis is both fraught with difficulty and yet of paramount importance given its far-reaching consequences, many of which are amenable to treatment. We discuss a patient who presented with hypokalemia and other electrolyte abnormalities suggestive of Fanconi syndrome whilst on adefovir for hepatitis B. A trans-tubular potassium gradient (TTKG = 9.4) and urinary fractional phosphate excretion (39.4 %) consistent with renal potassium and phosphate wasting together with euglycemic glycosuria, aminoaciduria and hypophosphatemic osteomalacia supported the diagnosis of adefovir-induced Fanconi syndrome. With the cessation of the culprit drug, the patient has achieved partial recovery after 9 months. A high index of suspicion coupled with regular symptom surveillance and electrolyte monitoring is recommended in the course of adefovir therapy.

Two Cases of Hypophosphatemic Osteomalacia After Long-term Low Dose Adefovir Therapy in Chronic Hepatitis B and Literature Review

Adefovir dipivoxil (ADV) is a nucleotide used as long-term therapy of chronic hepatitis B. Many published reports have shown that long-term high-dose therapy with adefovir can be associated with proximal renal tubular dysfunction resulting in significant hypophosphatemia, renal insufficiency and osteomalacia. We have encountered two patients who developed evidence of hypophosphatemic osteomalacia while on long-term low-dose adefovir therapy for chronic hepatitis B. We report on its clinical features and its potential resolution with cessation of the drug and supplementation with phosphate. We also reviewed the other published cases associated with hypophosphatemic osteomalacia after low-dose adefovir therapy. The symptoms and the hypophosphatemia improved after cessation of the drug and supplementation with phosphate in most cases. Patients taking adefovir long-term should receive regular investigation of the phosphate level and renal function.

Hypophosphatemic osteomalacia due to drug-induced Fanconi's syndrome associated with adefovir dipivoxil treatment for hepatitis B

We herein present the case of a 58-year-old Japanese man with Fanconi's syndrome with a 13-month history of bone pain in his ribs, hips, knees and ankles. He had been receiving low-dose adefovir dipivoxil (ADV) for the treatment of lamivudine-resistant chronic hepatitis B virus infection for eight years and subsequently developed severe hypophosphatemia and proximal renal tubule dysfunction. Magnetic resonance imaging showed multiple insufficiency fractures in the ribs, ileum, tibia and calcaneus. Whole-body bone scintigraphy demonstrated increased uptake in those areas. Following dose reduction of ADV and the administration of treatment with calcitriol and phosphates, the patient's serum phosphate level increased and his clinical symptoms improved. Physicians prescribing ADV should carefully monitor the renal function and serum phosphate level.

Hypophosphatemic osteomalacia and renal Fanconi syndrome induced by low-dose adefovir dipivoxil: a case report and literature review suggesting ethnic predisposition

WHAT IS KNOWN AND OBJECTIVE

Adefovir dipivoxil (ADV) is one of the commonly used antiviral agents in the treatment of chronic hepatitis B (CHB) infection. Safety of a daily dose of 10 mg ADV is advocated by the registration trials. We report a case of severe hypophosphatemic osteomalacia and renal Fanconi syndrome induced by low-dose ADV in a CHB-related cirrhosis patient, and discuss the case through a thorough review of other cases reported in the literature.

CASE SUMMARY

A 48-yr-old Chinese man with CHB-related cirrhosis developed severe progressive generalized bone pain and muscle weakness after receiving ADV 10 mg daily for 54 months. The laboratory results showed severe hypophosphatemia and features of proximal renal tubule dysfunction. Imaging studies were consistent with osteomalacia. After discontinuation of ADV, his symptoms resolved, laboratory abnormalities normalized and imaging studies showed improvement. In addition to our case, 12 other patients have been reported to have developed hypophosphatemic osteomalacia induced by low-dose ADV. Most of the reported cases were of subjects of East-Asian ethnicity. After discontinuation or reduction of ADV, serum phosphate level increased and clinical symptoms significantly improved in all cases.

WHAT IS NEW AND CONCLUSION

Hypophosphatemic osteomalacia and renal Fanconi syndrome can be associated with low-dose ADV. Clinicians treating CHB patients with ADV 10 mg daily over long periods of time should be aware of this infrequent but serious complication.

Hypophosphatemic osteomalacia induced by low-dose adefovir therapy: focus on manifestations in the skeletal system and literature review

Osteomalacia is a metabolic bone disease that leads to softening of the bones and can be caused by hypophosphatemia. Large clinical studies of low-dose adefovir dipivoxil (adefovir) have found no evidence of renal tubular dysfunction leading to hypophosphatemia after 48 weeks of treatment. We report two cases of low-dose adefovir-induced hypophosphatemic osteomalacia that initially presented with diffuse musculoskeletal pain. The first patient was a 62-year-old man with a 2-year history of bone pain involving the dorsal mid-thorax, lower anterior chest wall, right sacroiliac joint area, and both knees. The patient had been receiving adefovir for 5 years before confirmation of hypophosphatemia and urinary phosphate wasting. Bone scintigraphy revealed multifocal lesions including multiple ribs, costochondral junctions, costovertebral junctions, sacrum, both posterior iliac bones, both proximal tibia, right calcaneus, and the left second metatarsophalangeal joint area, which were suggestive of metabolic bone disorder. Bone pain was significantly reduced within 3 months after supplementation with phosphate and calcitriol. The second patient was a 54-year-old male who presented with an 18-month history of severe bone pain of the right medial knee and low back. The patient had been taking adefovir for approximately 40 months before the development of bone pain. Laboratory data revealed hypophosphatemia and vitamin D deficiency. Bone scintigraphy showed increased uptake in bilateral ribs, sternum, both scapulae, both costovertebral junctions, both pelvic bones, medial cortex of the right proximal femur, right proximal tibia, and the left lateral tarsal bone. The symptoms improved by changing the antiviral agent from adefovir to entecavir. Because osteomalacia often presents with diffuse bone pain, non-specific radiologic findings and non-characteristic routine serum biochemical changes, the disease can be confused with various musculoskeletal diseases and a high index of suspicion is necessary for an early diagnosis in patients receiving adefovir therapy.

Pathological femoral fractures due to osteomalacia associated with adefovir dipivoxil treatment for hepatitis B: a case report

We present a case of a 62-year-old man who underwent total hip arthroplasty for treatment of pathologic femoral neck fracture associated with adefovir dipivoxil-induced osteomalacia. He had a 13-month history of bone pain involving his shoulders, hips, and knee. He received adefovir dipivoxil for treatment of lamivudine-resistant hepatitis B virus infection for 5 years before the occurrence of femoral neck fracture. Orthopedic surgeons should be aware of osteomalacia and pathological hip fracture caused by drug-induced renal dysfunction, which results in Fanconi’s syndrome.