Thermal Ablation for Treating Tumor-induced Osteomalacia in a Patient With IV Phosphate Dependency

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome associated with tumors secreting fibroblast growth factor 23 that can be cured with complete surgical resection of the tumor. However, when these tumors are at difficult locations, less invasive modalities such as thermal ablation (TA) might be a good alternative. A 40-year-old woman was seen for a second opinion because of severe hypophosphatemia with complaints of fatigue, myalgia, and muscle weakness for which she needed IV phosphate for 15 to 18 hours per day in addition to oral alfacalcidol and phosphate. Initial laboratory results revealed hypophosphatemia (0.59 mmol/L [1.83 mg/dL]; reference range, 0.90-1.50 mmol/L [8.40-10.2 mg/dL]), increased fibroblast growth factor 23 levels (137 RU/mL; reference range, <125 RU/mL), and a reduced TmP-GFR (0.47 mmol/L; reference range, 0.8-1.4 mmol/L). Gallium-positron emission tomography/computed tomography (CT) showed moderately increased uptake at thoracic vertebra (Th) 8 and mildly increased uptake at Th7, suggestive of TIO. Complete tumor removal would have required resection of at least 1 vertebral body. Therefore, CT-guided TA was performed at Th8. No complications were observed, and in the months after, treatment with IV phosphate could be discontinued, indicating a satisfying result from the procedure. This extreme TIO case demonstrates that CT-guided TA can be an alternative to extensive or risky classical surgery.

Changes in Bone Mineral Density Following Conventional Oral Phosphonate Treatment of Hypophosphatemic Osteomalacia: A Non-Randomized Controlled Study

Purpose

There are limited clinical studies aimed at solving the problem of the efficiency of conventional treatment with oral phosphate and calcitriol in adults with hypophosphatemic osteomalacia (HO). In addition, there still had no good non-hazardous markers to evaluate the severity of bone loss of osteomalacia before and after treatment. Therefore, the purpose of this study was to assess the efficacy of conventional treatment with a self-blended phosphate supplementation and calcitriol on patients with HO and whether bone mineral density (BMD) can be helpful for monitoring the efficacy.

Patients and Methods

A total of 21 HO patients and 105 healthy controls were enrolled. All patients were tested for serum biomarkers and BMD of the lumbar spine (L1-L4), femoral neck, and total left hip. After three years of treatment, 11 of 21 HO patients were recalled for BMD measurement. According to the administration of drugs, HO patients with calcium and calcitriol were divided into three phosphate treatment groups: patients in group A (n = 3) received continuous phosphate supplementation, patients in group B (n = 5) received intermittent phosphate supplementation and patients in group C (n = 3) received no phosphate supplementation.

Results

The diagnoses of 21 HO patients were 5 cases of hereditary hypophosphatemic rickets, 4 cases of Fanconi syndrome with the features of renal tubular acidosis and vitamin D deficiency, and 12 cases of hereditary vitamin D abnormality. The average initial serum phosphorus level of the patient group was approximately 50% lower than that of the control group. Lower BMD was significantly observed in the HO group than the control group at the lumbar spine and total hip. Continuous treatment with the phosphate supplement could increase BMD in the lumbar spine and total hip by 33.4-52.3% and in the femoral neck increased by 43.2-79.3% compared with baseline, and the effect appears to be continued once treatment is discontinued.

Conclusion

These findings suggest that conventional therapy can improve bone mineral defects in patients with HO, especially in the femoral neck. Detection of BMD in HO patients is a good tool to assess the extent of bone defects and the therapeutic effect.

Trial Registration

Chinese Clinical Trial Registry, ChiCTR-OOC-16010095. Registered 7 December 2016. Retrospectively registered.

Fanconi Syndrome Leading to Hypophosphatemic Osteomalacia Related to Tenofovir Use

Tenofovir disoproxil fumarate (TDF) is used worldwide to treat and prevent Human Immunodeficiency Virus (HIV) infection. Fanconi syndrome is a complication of TDF use and is characterized by inadequate reabsorption of glucose, phosphate and protein in the proximal tubule of the kidney which may eventually lead to osteomalacia manifested by symptoms of pain, muscular weakness and difficulty ambulating. We present a patient with severe osteomalacia due to progressive and unrecognized Fanconi's syndrome, who responded rapidly to TDF withdrawal, oral phosphate repletion and calcitriol. With the widespread use of TDF-containing antiviral regimens, it is critically important that physicians adhere to screening recommendations to detect early Fanconi syndrome, and recognize symptoms of osteomalacia as a serious complication.

Hypophosphataemic osteomalacia due to cadmium exposure in the silver industry

Chronic heavy metal exposure and the health hazards that ensue are important public-health problems. We highlight the occurrence of hypophosphataemic osteomalacia due to chronic cadmium exposure in the silver industry in India. Three silversmiths presented similarly with clinical, biochemical and radiological evidence of hypophosphataemic osteomalacia. Considering their occupation, their blood samples were screened for heavy metals and were found to have toxic levels of cadmium. They were initiated on neutral phosphate and calcitriol. On follow-up, they reported significant reduction in severity of symptoms. It is essential to maintain a high index of suspicion in diagnosing this condition. A thorough knowledge of the occupational background of patients, as well as ambient conditions at the workplace is of utmost importance in contemplating the possibility of such rare occurrences. Moreover, regulatory agencies and policy makers ought to survey the silver industry and ensure that the metals used are within permissible safe limits of exposure.

Clinical features of hypophosphatemic osteomalacia induced by long-term low-dose adefovir dipivoxil

Objective

To investigate the predictors of hypophosphatemic osteomalacia induced by adefovir dipivoxil (ADV) and to monitor for early detection.

Patients and methods

Hospitalized patients who were diagnosed with ADV-related hypo-phosphatemic osteomalacia were recruited and retrospectively analyzed in our hospital from January 2012 to December 2016. A telephone interview was conducted at 1, 3, 6, 9, 12, and 24 months after cessation of ADV.

Results

In the 8 patients enrolled in the study, the hypophosphatemic osteomalacia symptoms developed at an average of 5.14 (4–7) years since ADV treatment (10 mg/d). The average alkaline phosphatase (ALP) level was 279.50 (137–548) U/L, which was significantly higher than the normal level (45–125 U/L). The serum phosphorus level was an average of 0.59 (0.43–0.69) mmol/L, which was lower than the normal range (2.06–2.60 mmol/L). Serum calcium levels of the enrolled patients remained within normal limits. Reduced estimated glomerular filtration rate (eGFR <29 mL/min/1.73 m²) was seen in 4 cases. The clinical manifestations were mainly progressive systemic bone and joint pain, frequent fractures, trouble in walking, height reduction (4–6 cm), and so on. After cessation of ADV, symptoms like bone pain resolved gradually. Serum phosphorus level restored to normal in 4.5 months after the withdrawal of ADV. However, in 4 patients, renal function failed to return to normal in 24 months.

Conclusion

More attention should be paid to the duration of ADV treatment. The level of serum phosphorus and ALP, as well as renal function, should be monitored for early detection of potential adverse drug reactions.

Adult-onset hypophosphatemic osteomalacia associated with Sjogren syndrome: Clinical case report

RATIONALE

Hypophosphatemic osteomalacia (HO) is a metabolic bone disease, exhibiting different etiologies such as genetic mutation, tumor induction, dysimmunity, or renal disease. Sjogren's syndrome (SS) is a connective tissue disorder commonly involving exocrine glands; however kidney involvement is also encountered, leading to abnormal phosphorus metabolism, even HO.

PATIENT CONCERNS

A 47-year-old female patient presented progressively worsening pain in the chest wall, back and bilateral lower extremities as well as muscle weakness was referred to our department.

DIAGNOSES, INTERVENTIONS AND OUTCOMES

Due to the laboratory test results, radiographic findings and pathologic results, she was diagnosed with adult-onset HO associated with SS. She was then treated with alkalinization, steroids, neutral phosphate, calcium supplements together with activated vitamin D. So far, she recovered uneventfully with relieved pain and increased serum phosphorus level.

LESSONS

HO may be secondary to renal tubular acidosis of SS patients, and it might be a diagnostic challenge when the kidney involvement in SS is latent and precede the typical sicca symptoms.

Nephrogenic hypophosphatemic osteomalacia during adefovir monotherapy for chronic hepatitis B monoinfection

BACKGROUND

In this paper, we explore nephrogenic hypophosphatemic osteomalacia associated with low-dose adefovir dipivoxil (ADV) therapy.

METHODS

Five patients who were treated with ADV for >2 years were included in this study. The metabolic index of phosphate and calcium, renal tubular function, renal function and pathological changes of the patients were investigated.

RESULTS

Two male and three female patients were studied. All of the patients presented with a reduced serum phosphate level (0.38-0.60 mmol/L) accompanied with hyperphosphaturia at 10.9-23.8 mmol/24 h. The serum potassium level was also reduced or at lower range (2.56-3.54 mmol/L), but the 24-h urinary potassium was relatively increased. Urinalysis also demonstrated increased excretion of glucose in four patients. Urine protein electrophoresis showed low-to-moderate molecular weight protein. Three patients manifested urine acidification function impairment. Four patients had accompanying renal insufficiency. Three patients had difficulty walking and presented with a reduction in height (2.5-14 cm). Renal biopsy revealed that most of the glomeruli were normal accompanied by mild interstitial fibrosis with inflammatory cell infiltration. ADV treatment was subsequently ceased. Patients were treated with regular phosphate supplementation, citrate acid potassium and calcium bicarbonate. After 6-month treatment, the bone pain was significantly alleviated. Serum creatinine of one patient returned to normal levels and two patients who had difficulty walking were able to walk independently.

CONCLUSIONS

The current study showed long-term and low-dose ADV treatment in a Chinese population may lead to proximal tubular impairment, metabolic acidosis, hypophosphatemia, hypokalemia, metabolic bone disease, renal osteopathia and renal functional damage.

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.

Oncogenic osteomalacia: Problems in diagnosis and long-term management

Oncogenic osteomalacia is a rare association between mesenchymal tumors and hypophosphatemic rickets. It is more of a biochemical entity than a clinical one. The pathophysiology of the tumor is not clear. However, it has been seen that the clinical and biochemical parameters become normal if the lesion responsible for producing the osteomalacia is excised. For a clinical diagnosis a high index of suspicion is necessary. We present three such cases where in one the oncogenic osteomalacia reversed while in rest it did not. We present this case report to sensitize about the entity.

Patients with Hypophosphatemic Osteomalacia Need Continuous Treatment during Adulthood

The treatment for hypophosphatemic rickets in children includes phosphate and vitamin D preparations. In children, this regimen significantly improves symptoms, while a treatment for adult patients has not been established. We therefore investigated the clinical courses of 15 adult patients who discontinued therapy when final height was achieved in order to assess the necessity of treatment in adulthood. Thirteen patients developed symptomatic complications, including bone fractures. Among the 13, the 10 patients who restarted therapy all showed clinical improvement, and no side effects of treatment were observed. This study shows that there are some patients with hypophosphatemic osteomalacia who need continuous treatment during adulthood.