Nutritional status of hemodialysis patients with secondary hyperparathyroidism

Hyperparathyroidism, Serum Phosphorus and Dietary Intake in Hemodialysis Patients: Is There a Novel Relationship?

The management of hyperparathyroidism (intact parathyroid hormone (iPTH) serum levels > 585 pg/mL), frequently focuses on the appropriate control of mineral and bone markers, with the decrease in serum and dietary phosphorus as two of the targets. We aimed to investigate the association between iPTH, serum phosphorus levels and dietary intake. This was a cross-sectional, multicenter, observational study with 561 patients on hemodialysis treatment. Clinical parameters, body composition and dietary intake were assessed. For the analysis, patients were divided into three groups: (a) iPTH < 130, (b) iPTH between 130 and 585 and (c) iPTH > 585 pg/mL. The association between PTH, serum phosphorus and dietary intake was analyzed using linear regression models. In the whole sample, 23.2% of patients presented an iPTH > 585 pg/mL. Patients with higher iPTH levels were those with longer HD vintage and lower ages, higher serum phosphorus, serum calcium, Ca/P product, albumin and caffeine intake, and a lower dietary intake of phosphorus, fiber, riboflavin and folate. Higher serum phosphorus predicted higher iPTH levels, even in the adjusted model. However, lower dietary phosphorus and fiber intake were predictors of higher iPTH levels, including in the adjusted model. Our results bring new data to the relationship between dietary intake and iPTH values. Despite higher serum phosphorus being observed in patients with HPTH, an opposite association was noted regarding dietary phosphate and fiber.

Muscle strength, physical performance, and metabolic changes after subtotal parathyroidectomy for secondary hyperparathyroidism

BACKGROUND

Hyperparathyroidism in patients on chronic hemodialysis presents with bone pain, pruritus, and extra-skeletal calcifications. Little attention has been paid to low plasma protein concentrations and muscle weakness in these patients. The present study was undertaken to characterize the impact of subtotal parathyroidectomy for chronic hemodialysis on body composition, muscle strength, plasma proteins, quality of life, and long-term clinical course.

METHODS

We performed a prospective observational before-after assessment study of consecutive chronic hemodialysis patients referred for parathyroidectomy. Patients were investigated at baseline before parathyroidectomy and then at 1 and 6 months after surgery, with the aim to assess changes in metabolic parameters, body composition by bioimpedance, muscle strength, and quality of life (36-items Short Form Health Survey questionnaire). Follow-up was terminated when patients reached 1 of the 3 pre-defined end points: recurrence of secondary hyperparathyroidism, transplantation, or death.

RESULTS

A group of 23 patients on hemodialysis were included. Preoperative handgrip strength was diminished by 52.4 ± 17%. After parathyroidectomy, a drop of immunoreactive parathyroid hormone concentrations (1,153 vs 237 pg/mL; P < .001) was observed together with increases in plasma protein (total: 6.8 vs7.8 g/dL, s-albumin 3.7 vs 4.4 g/dL and prealbumin: 31.7 vs 35.2 mg/dL; P < .001), handgrip strength (18.3 vs 22.9 kg: P = .001) as well as an improvement in physical dimension (32.9 vs 35.6; P = .004) and vitality (32.3 vs 47.1; P = .002) domains of the 36-items Short Form Health Survey questionnaire. After10 years, one-third of the patients had died, one-third of the patients had a recurrence of secondary hyperparathyroidism, and one-third of patients had received a kidney transplant and maintained a normal parathyroid function.

CONCLUSION

Subtotal parathyroidectomy improves protein metabolic markers, muscle strength, and physical performance in chronic hemodialysis patients.

Influence of nutritional status on serum large N-truncated PTH, but not PTH(1–84) in hemodialysis patients

BACKGROUND

Serum level of parathyroid hormone (PTH), measured by second-generation intact PTH (I-PTH), is known to be associated with nutritional status in hemodialysis (HD) patients. We investigated whether PTH(7-84) and larger N-truncated PTH or PTH(1-84) might be affected by nutritional status in HD patients.

METHODS

Serum PTH was determined in 170 male HD patients by either a Bio-intact PTH (Bio-PTH) or I-PTH assay. Lean body mass in the trunk region was measured as a nutritional marker by dual X-ray absorptiometry.

RESULTS

The serum PTH(7-84) level was theoretically obtained from the difference between serum I-PTH and Bio-PTH because I-PTH assay cross-reacted with PTH(7-84) with the same degree as PTH(1-84), although N-truncated PTH fragment larger than PTH(7-84) might affect theoretical serum PTH(7-84) level, although slightly. Serum PTH(1-84) was directly obtained from the serum Bio-PTH value because of its exclusive reaction with PTH(1-84). Serum PTH(7-84) correlated significantly with nutritional markers such as body weight, albumin, protein catabolic rate (PCR), TACBUN, BUN, phosphate, and lean body mass in the trunk, whereas PTH(1-84) correlated only with phosphate. Multiple regression analysis revealed that PCR, body weight, and lean body mass in the trunk region are significant factors independently associated with PTH(7-84), but not with PTH(1-84).

CONCLUSIONS

The results suggest that serum levels of PTH(7-84) and larger N-truncated PTH fragments, but not PTH(1-84), might be affected by the nutritional state in HD patients, which might explain the reported correlation of serum I-PTH levels with nutritional markers.

Influência do hiperparatireoidismo secundário grave no estado nutricional de pacientes com insuficiência renal crônica

OBJETIVO: Avaliar o efeito do paratormônio na ingestão alimentar e sua relação com a composição corporal de pacientes em programa de hemodiálise com hiperparatireoidismo secundário. MÉTODOS: Foram avaliados 26 pacientes adultos, com média de idade de 47 ± 8 anos, divididos em dois grupos, de acordo com os níveis de paratormônio, e pareados por sexo. No grupo 1 (n=3) os níveis de paratormônio eram maiores que 300pg/ml (1.486±920pg/ml), e no grupo 2 (n=13), menores que 300pg/ml (199,8±122,2pg/ml). Todos os pacientes realizaram registro alimentar de três dias, medidas antropométricas e exames bioquímicos séricos para avaliar o metabolismo ósseo. RESULTADOS: Os pacientes do grupo 1 apresentaram índice de massa corporal, porcentagem da circunferência muscular do braço, da prega cutânea triciptal e de gordura corpórea, significativamente menores que os pacientes do grupo 2 (p<0,05). Houve correlação negativa e significante entre o paratormônio e a gordura corporal (r=-0,6; p<0,05). Em adição, a análise de regressão linear múltipla mostrou que o paratormônio, junto com o tempo em diálise, explicam em 42% a diminuição da gordura corporal total. Quanto à ingestão de nutrientes e aos marcadores bioquímicos, com exceção do paratormônio, não houve diferença estatisticamente significante entre os dois grupos. As ingestões de energia, proteína e cálcio estavam abaixo das recomendações para pacientes em diálise, e a ingestão de fósforo foi em média 11 ± 6mg/kg/dia e 15 ± 5mg/kg/dia, e considerada adequada para esta população. CONCLUSÃO: Com ingestão alimentar semelhante, quanto maior o nível de paratormônio e o tempo em diálise, menor é a gordura corporal nos pacientes com hiperparatireoidismo secundário grave, o que mostra que níveis altos de paratormônio contribuem para alterações no estado nutricional nestes pacientes.