Tenofovir monotherapy for hepatitis B after 1 year does not produce renal dysfunction, but is associated with hyperparathyroidism not related to vitamin D

Biochemical Markers of Calcium and Bone Metabolism during and after Lactation in Ugandan Women with HIV on Universal Maternal Antiretroviral Therapy

We reported accentuated lactational decreases in areal bone mineral density and only partial skeletal recovery after lactation in Ugandan women with HIV (WWH) initiated on tenofovir disoproxil fumarate-based antiretroviral therapy (TDF-based ART) during pregnancy compared to women without HIV (REF). WWH also had higher breast milk calcium in the first months of lactation. To investigate the mechanisms, we measured bone turnover markers (bone resorption: C-terminal telopeptide [CTX]; bone formation: procollagen type 1 N-terminal propeptide [P1NP], bone-specific and total alkaline phosphatase [BALP, TALP]), hormones (parathyroid hormone [PTH], intact fibroblast growth factor 23 [FGF23], 1,25-dihydroxyvitamin D [1,25(OH)2 D]), vitamin D status (25-hydroxyvitamin D [25OHD]), and indices of mineral metabolism and renal function. Blood and urine samples collected at 36 weeks of gestation, 14 and 26 weeks of lactation, and 3-6 months after lactation were analyzed. Mean 25OHD was >50 nmol/L throughout. Both groups experienced similar biochemical changes during pregnancy and lactation to women in other settings, but within these patterns, the two groups differed significantly. Notably, WWH had higher PTH (+31%) and lower 1,25(OH)2 D (-9%) and TmP/GFR (-9%) throughout, lower P1NP (-27%) and plasma phosphate (-10%) in pregnancy, higher CTX (+15%) and BALP (+19%), and lower eGFR (-4%) during and after lactation. P1NP/CTX ratio was lower in WWH than REF in pregnancy (-21%), less so in lactation (-15%), and similar after lactation. Additionally, WWH had lower plasma calcium (-5%), lower FGF23 (-16%) and fasting urinary calcium (-34%) at one or both lactation timepoints, and higher fasting urinary phosphate (+22%) at 26 weeks of lactation and after lactation. These differences resemble reported TDF effects, especially raised PTH, increased bone resorption, decreased bone formation, and decreased renal function, and may explain the observed differences in bone mineral density and breast milk calcium. Further studies are needed to determine whether HIV and TDF-based ART have long-term consequences for maternal bone health and offspring growth. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Tenofovir-induced osteopenia and hyperparathyroidism: A case report and literature review

Tenofovir disoproxil fumarate is the first-line antiviral therapy for chronic viral hepatitis B, but long-term use is associated with renal failure and hypophosphatemic osteomalacia. Tenofovir disoproxil fumarate-induced osteoporosis and secondary hyperparathyroidism are less commonly reported. Herein, we describe the case of a patient with bone and multijoint pain who was initially misdiagnosed as having normocalcemic primary hyperparathyroidism associated with prolonged exposure to tenofovir disoproxil fumarate. The patient's 24-h urinary calcium and phosphorus excretion levels and serum calcium levels were at the lower end of the normal range. After reviewing these findings, the diagnosis was amended to osteoporosis and secondary hyperparathyroidism caused by tenofovir disoproxil fumarate. In this report, we describe the differences in clinical and laboratory manifestations of hyperparathyroidism induced by tenofovir disoproxil fumarate and normocalcemic primary hyperparathyroidism. We also discuss relevant pathophysiological mechanisms and propose a feasible treatment strategy.

Is urinary β2-microglobulin a reliable marker for assessment of renal tubular dysfunction in chronic hepatitis B patients receiving tenofovir therapy?

BACKGROUND AND AIM

Urinary β2-microglobulin (β2-M) is a marker for renal tubular dysfunction. The current study aimed to assess urinary β2-M as a reliable marker for early prediction of tenofovir disoproxil fumarate (TDF)-related nephrotoxicity among hepatitis B virus (HBV) patients.

METHODS

Forty-two HBV patients who were a candidate for TDF therapy or have recently started it (for less than 6 months) were enrolled and subjected to demographic, clinical, laboratory assessment, abdominal ultrasound and transient elastography. The glomerular filtration rate (GFR) was estimated using the Cockcroft-Gault equation. Also, urinary β2-M was measured by the ELISA method within 6 months after the introduction of TDF treatment and 6 months later.

RESULTS

Mean age was 41.8 (9.55) years, 27 were males and 59.5% of patients have elevated urinary β2-M after 6 months follow-up of TDF therapy. Urinary β2-M was 0.07 ± 0.07 μg/ml at baseline and insignificantly increased up to 0.09 ± 0.08 μg/ml after 6 months follow-up. Despite the insignificant increase in serum creatinine from 0.85 ± 0.23 mg/dl at baseline to 0.9 ± 0.21 mg/dl after 6 months and the insignificant decrease in eGFR from 126.2 ± 39.72 ml/min at baseline and 117.64 ± 42.23 ml/min at 6 months follow-up. No correlation was found between the changes in urinary β2-M and the changes in other renal function indices at baseline and 6 months follow-up.

CONCLUSIONS

Short-term TDF therapy is associated with nonsignificant changes either in eGFR or urinary β2-M; these changes are not clinically relevant that indicates disease progression. Therefore, the suitability of urinary β2-M as a screening tool for tenofovir induced tubular dysfunction should be further.

Value of Cystatin C-Based e-GFR Measurements to Predict Long-Term Tenofovir Nephrotoxicity in Patients With Hepatitis B

BACKGROUND

Cystatin C is a genuine marker for detecting minor reductions in estimated glomerular filtration rate (e-GFR).

STUDY QUESTION

We aimed to investigate the efficiency of cystatin C levels in predicting nephrotoxicity due to antiviral therapy in patients with chronic hepatitis B virus infection.

STUDY DESIGN

Seventy-six naive hepatitis B virus patients and 44 controls were enrolled in this prospective cohort study.

MEASURES AND OUTCOMES

Serum cystatin C, phosphate and creatinine levels, and urinary albumin/creatinine ratios of all patients were measured at baseline, 3rd, 12th, and 24th months. Nephrotoxicity was determined according to the amount of change in creatinine level at the fourth year of treatment compared with baseline ([INCREMENT]Cr0-4).

RESULTS

Mean age was 36.1 ± 9.2 years and 40 (52.2%) of patients were women. There was no significant difference between baseline values of tenofovir disoproxil fumarate and entecavir groups. Although the creatinine level at the fourth year of treatment was statistically nonsignificant compared with baseline in the entecavir group, it was significantly higher in the fourth year of tenofovir treatment compared with baseline (0.95 ± 0.27 mg/dL vs. 0.76 ± 0.16 mg/dL, P = 0.002). While the increase in [INCREMENT]Cr0-4 was ≥0.2 mg/dL in 43.2% of patients in the tenofovir group, this rate was 18.8% in the entecavir group. Diagnostic accuracy in identifying decreased renal function as area under the curve (AUC) was high for baseline serum cystatin C level; furthermore, the highest AUC was calculated for cystatin C plus creatinine-based e-GFR equation (AUC: 0.81, P < 0.001).

CONCLUSIONS

Long-term tenofovir disoproxil fumarate nephrotoxicity can be predicted by serum cystatin C plus creatinine-based e-GFR measured before treatment.

Tenofovir Disoproxil Fumarate Is Associated with a Set-Point Variation in the Calcium-Parathyroid Hormone-Vitamin D Axis: Results from a German Cohort

Background

Higher levels of parathyroid hormone have been associated with the use of tenofovir disoproxil fumarate (TDF) in people with and without HIV infection. Yet, alterations in calcium levels have never been elucidated in detail.

Objective

To compare the association of parathyroid hormone with serum calcium levels and other markers of calcium and bone metabolism in people living with HIV on TDF- and non-TDF-containing antiretroviral therapy.

Patients and Methods

A retrospective single center cohort study in Munich, Germany. Median and interquartile ranges and absolute and relative frequencies were used to describe continuous and categorical variables, respectively. The Mann–Whitney U test and chi²-test were used for comparisons. Multivariate median regression was performed in a stepwise backward approach.

Results

1,002 patients were included (786 (78.4%) male; median age 48 (40–55) years). 564 patients (56.3%) had a TDF-containing ART regimen. PTH concentrations were 46.9 (33.0–64.7) pg/mL and 35.2 (26.4–55.4) pg/mL (P=0.001), 43.3 (30.8–59.8) pg/mL and 31.8 (22.3–49.6) pg/mL (P < 0.001), 46.1 (29.5–65.4) pg/mL and 33.4 (22.6–50.1) pg/mL (P < 0.001), and 37.8 (25.3–57.9) pg/mL and 33.8 (20.1–45.3) pg/mL (P=0.012) within the first, second, third, and fourth quartile of corrected calcium levels for patients with and without TDF-containing ART, respectively. In multivariate median regression, PTH concentration was significantly associated with Ca_corr. (−32.2 (−49.8 to −14.8); P < 0.001), female sex (5.2 (1.2–9.2); P=0.010), 25(OH)D (−0.4 (−0.5 to −0.3); P < 0.001), and TDF-use (9.2 (6.0–12.5); P < 0.001).

Discussion

Higher levels of PTH seem to be needed to maintain normal calcium levels in PLWH on TDF-containing ART compared to non-TDF-containing ART. Optimal concentrations for 25-hydroxy vitamin D and calcium might therefore be different in people using TDF than expected from general populations but also people living with HIV with non-TDF-containing antiretroviral therapy. This might require different supplementation strategies but warrants further investigation.

Tenofovir disoproxil fumarate/emtricitabine is associated with a higher risk of hypocalcemia compared to abacavir/lamivudine - results from a German cohort study

Hyperparathyroidism has been described in people living with HIV undergoing tenofovir disoproxil fumarate (TDF)-containing antiretroviral therapy (ART), but differences in calcium levels have never been investigated in detail. We aimed to compare the prevalence of hypocalcemia between patients with and without TDF-containing ART. The patients and methods were a retrospective cohort study in HIV-infected adult patients receiving dolutegravir and either abacavir (ABC)/lamivudine (3TC) or TDF/emtricitabine in a single center in Munich, Germany. Of 172 patients, 126 (73.3%) were male and the median age was 48.5 years (interquartile range 42-54). Average calcium levels were 2.24 (2.21-2.29) mmol/l and 2.21 (2.16-2.26) mmol/l (P < 0.001) with a prevalence of at least one episode of total calcium <2.12 mmol/l of 16.2 and 34.4% in the groups treated with ABC/3TC and TDF/emtricitabine, respectively (P = 0.006). TDF use was independently associated with the occurrence of albumin-corrected calcium levels of <2.12 mmol/l (odds ratio: 6.7 [1.3-35.6]; P = 0.025). Hypocalcemia seems to occur more often in TDF-treated patients. Further research into hypocalcemia with TDF and potential cardiovascular effects may be of benefit based on these findings.

Patterns of vitamin D, parathyroid hormone and c-terminal telopeptide of collagen type 1 in Caucasian and African descent HIV-infected populations in Central Europe

Risk factors for bone loss in HIV patients might differ or have a different impact in African descent compared to Caucasian populations. The aim of the paper is to analyze the relevance of risk factors on surrogate markers of bone metabolism in HIV-infected African descent and Caucasian patients. This is a cross-sectional study in a single HIV-specialized research and clinical care center in Munich, Germany. We included 889 patients in the study, among them 771 Caucasians (86.7%). Only in Caucasians lower vitamin D levels [OR: 2.5 (95CI: 1.6-3.7)], lower calcium levels [OR: 1.8 (1.2-2.8)], and the use of tenofovir disoproxil fumarate [OR: 2.8 (1.8-4.4)] were significantly associated with elevated PTH in multivariate analysis. Likewise, only in Caucasians elevated PTH was significantly associated with elevated markers of c-terminal telopeptides of collagen type 1 (β-CTX) [OR: 1.7 (1.0-3.0)]. Effects of traditional risk factors for secondary hyperparathyroidism and increased markers of bone turn-over seem to be less distinct in African descent HIV patients. The clinical impact and generalizability of this finding as well as the significance of vitamin D supplementation in African descent patients therefore warrants further investigation.

Treatment of chronic hepatitis B with tenofovir

Tenofovir (TDF) is a potent hepatitis B virus (HBV) inhibitor with a high barrier to drug resistance, and it has been recommended as one of the first-line drugs to treat chronic hepatitis B (CHB). This paper reviews the recent advances in the treatment of CHB with TDF, especially in terms of its efficacy as first-line and second-line antiviral therapies as well as its role in the prevention of mother-to-child HBV transmission.