Responsividade paratireoideana à hipocalcemia após paratireoidectomia total com autoimplante em portadores de hiperparatireoidismo associado à doença renal crônica / Parathyroid responsiveness during hypocalcemia after total parathyroidectomy and autotransplantation in patients with renal hyperparathyroidism

Resumo Introdução: O hiperparatireoidismo é uma complicação frequente da doença renal crônica (DRC). A paratireoidectomia (PTX) total com autotransplante (AT) de tecido paratireoideano é uma opção terapêutica para os indivíduos que não respondem ao manejo clínico. Objetivo: Avaliar a resposta do tecido paratireoideano enxertado durante hipocalcemia induzida em pacientes portadores de DRC submetidos à PTX total com AT. Métodos: Dezoito pacientes portadores de hiperparatiroidismo associado à DRC foram submetidos à PTX total com AT de tecido paratireoideano selecionado por estereomicroscopia entre Abril e Outubro de 2008 em nosso serviço. Onze indivíduos (oito com transplante renal funcionante, 2 em diálise peritoneal e 1 em hemodiálise) apresentavam boa condição clínica e foram elegíveis para o teste. Induziu-se hipocalcemia por infusão de bicarbonato de sódio em 5 controles normais e nos pacientes 6-12 meses após a PTX. Resultados: A hipocalcemia determinou um aumento importante dos níveis de PTH intacto (iPTH) no grupo controle 4 minutos após a infusão de bicarbonato. Nos pacientes, houve uma redução significativa do cálcio ionizado [de 1,17 ± 0,12 para 1,09 ± 0,11 (media ± EP) mmol/L] no 4º minuto (p < 0,001) ilustrando o nadir do teste. No 10º minuto não houve elevação do cálcio ionizado comparado ao 4º minuto (p = 0,451). Os níveis de iPTH foram de 34,8 ± 18,6 para 34,1 ± 18,8 pg/mL (valor basal semelhante ao 4º minuto p = 0,087) e se mantiveram no 10º minuto (33,3 ± 19,6 pg/mL p = 0,693). Conclusão: Em pacientes portadores de DRC testados 6-12 meses depois da cirurgia, o enxerto de tecido paratireoideano revelou incapacidade de resposta à hipocalcemia induzida por bicarbonato sem mudança dos níveis de iPTH.

Abstract Introduction: Hyperparathyroidism is a frequent complication of chronic kidney disease (CKD). Total parathyroidectomy (PTX) with parathyroid tissue autotransplantation (AT) is a treatment option in those individuals that do not respond to clinical management. Objective: To evaluate grafted parathyroid tissue response during induced hypocalcemia among CKD patients who underwent total PTX with AT. Methods: Eighteen patients with renal hyperparathyroidism were submitted to total PTX with parathyroid AT selected by stereomicroscopy between April and October 2008. Eleven (eight with successful kidney transplantation, 2 in peritoneal dialysis and 1 in hemodialysis) were clinically stable and eligible for testing. Hypocalcemia was induced using sodium bicarbonate infusion in 5 healthy controls and in patients 6-12 months after surgery. Results: Among controls, hypocalcemia elicited a major rise in intact PTH (iPTH) levels 4 minutes after bicarbonate infusion. In patients, a significant decrease in ionized calcium concentration was observed [from 1.17 ± 0.12 to 1.09 ± 0.11 mean (± SE) mmol/L] in the 4th minute (p < 0.001) illustrating the nadir point. In the 10thminute, ionized calcium did not show a statistical increase compared to the 4th minute (p = 0.451). The iPTH levels ranged from 34.8 ± 18.6 to 34.1 ± 18.8 pg/mL (similar values between base line and 4thminute p = 0.087) and did not change in the 10th minute (33.3 ± 19,6 pg/ mL p = 0.693). Conclusion: Among CKD patients tested 6-12 months after surgery, grafted parathyroid tissue revealed a blunted secretory capacity during bicarbonate induced hypocalcemia with no changes in iPTH levels.

Hipocalcemia: complicación en cirugía endocrino-metabólica: a propósito de un caso / Hypocalcemia: complication in surgery endrocrine-metabolica: a purpose of a case

La hipocalcemia es una complicación metabólica común en la tiroidectomía total y en el bypass gástrico. El mecanismo que la provoca es diferente en ambas entidades clínicas. La incidencia de esta complicación es variable, la presentación clínica es inespecífica y el manejo farmacológico no está estandarizado. Se presenta el caso clínico de una paciente de 40 años, a la cual se le realizaron ambas cirugías con el desarrollo de hipocalcemia sintomática post-operatoria.

Hypocalcemia is a common metabolic complications in total thyroidectomy and gastric bypass. The mechanism that causes it is different in both clinical entities. The incidence of this complication is variable, the clinical presentation is nonspecific and pharmacological management is not standardized. A case report of a patient of 40 years which were performed both surgeries with the development of postoperative symptomatic hypocalcemia.

Congenital rickets presenting with hypocalcaemic seizures

At Ataturk University Hospital, eight infants who presented with hypocalcaemic seizures were subsequently found to have rickets. Their mothers had osteomalacia. Neither mothers nor infants received vitamin D supplementation. Maternal vitamin D deficiency and non-supplementation in the infants were causes of rickets in these patients. It is recommended that neonatal hypocalcaemia may be due to maternal vitamin D deficiency and all unsupplemented vitamin D infants presenting with seizures should be investigated for rickets.

Extracellular calcium-sensing receptor: structural and functional features and association with diseases

The recently cloned extracellular calcium-sensing receptor (CaR) is a G protein-coupled receptor that plays an essential role in the regulation of extracellular calcium homeostasis. This receptor is expressed in all tissues related to this control (parathyroid glands, thyroid C-cells, kidneys, intestine and bones) and also in tissues with apparently no role in the maintenance of extracellular calcium levels, such as brain, skin and pancreas. The CaR amino acid sequence is compatible with three major domains: a long and hydrophilic aminoterminal extracellular domain, where most of the activating and inactivating mutations described to date are located and where the dimerization process occurs, and the agonist-binding site is located, a hydrophobic transmembrane domain involved in the signal transduction mechanism from the extracellular domain to its respective G protein, and a carboxyterminal intracellular tail, with a well-established role for cell surface CaR expression and for signal transduction. CaR cloning was immediately followed by the association of genetic human diseases with inactivating and activating CaR mutations: familial hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism are caused by CaR-inactivating mutations, whereas autosomal dominant hypoparathyroidism is secondary to CaR-activating mutations. Finally, we will comment on the development of drugs that modulate CaR function by either activating (calcimimetic drugs) or antagonizing it (calcilytic drugs), and on their potential therapeutic implications, such as medical control of specific cases of primary and uremic hyperparathyroidism with calcimimetic drugs and a potential treatment for osteoporosis with a calcilytic drug

Hipocalcemia / Hypocalcemia

A hipocalcemia está sendo diagnosticada mais freqüentemente pelos clínicos, e a conduta depende do conhecimento da sua fisiopatologia. A manutenção da calcemia dentro da normalidade é o resultado da interação do PTH e da vitamina D sobre o osso, rim e o intestino. O receptor de sensor de cálcio deve ser incluído na sua análise. O diagnóstico é realizado pela dosagem de cálcio, ou melhor, do cálcio ionizado. O diagnóstico diferencial entre várias causas de hipocalcemia pode ser realizado, permitindo um tratamento direcionado. Nesta revisão, veremos os mecanismos responsáveis no diagnóstico diferencial e a terapêutica apropriada.

Serum level of calcium in neonates with convulsion

A total of 65 [29 male and 36 female] neonates with convulsion were included in this study. Venous blood samples were obtained for the determination of serum calcium level using a flame atomic absorption spectrophotometry. The results show that 9.2% of the neonates with convulsion were hypocalcemia while 90.8% of the patients were normocalcemic. The results indicate that hypocalcemia is a minor cause of neonatal convulsion

Hipocalcemia neonatal / Neonatal hipocalcemy

A hipocalcemia neonatal e um disturbio metabolico relativamente frequente. Com o objetivo de atualizar sua definicao, classificacao, grupos de risco mais importantes e metodos diagnosticos, esta revisao foi realizada. Avaliou-se tambem a resposta fisiologica de recem-nascidos de termo adequados para a idade gestacional e as variacoes, presentes em alguns grupos de recem-nascidos, que contribuem para a ocorrencia da hipocalcemia. Foram propostos tratamentos especificos para hipocalcemia precoce e tardia e revista a validade da terapeutica profilatica para o quadro precoce.

Successful use of 1-alpha calcidiol in the treatment of generalized pustular psoriasis with hypocalcemia

Since the original description of generalized pustular psoriasis by Von Zumbusch, there have been different hypotheses regarding its pathogenesis. Hypocalcaemia is a known interesting manifestation which sometimes appears to be secondary to this condition and on other occasions a known precipitant. We report a patient who developed generalized pustular psoriasis associated with hypocalcaemia with a favourable response to 1-alpha calcidol therapy

Diagnóstico y tratamiento de la hipocalcemia / Diagnosis and treatment of hypocalcemia

LA hipocalcemia produce manifestaciones clínicas bien definidas, que abarcan una amplia gama desde parestesias periorales transitorias hasta tetania franca, convulsiones, arritmias y muerte. Son múltiples las causas de hipocalcemia y el tratamiento definitivo varia con la anomalia subyacente. En este artículo se analiza el enfoque diagnóstico de la hipocalcemia y con la base en las alteraciones fisiopatológicas responsables de la misma se establecen las medidas terapéuticas tanto para los casos agudos como para el tratamiento a largo plazo de estos pacientes.

Serum parathormone 25 hidroxicholecalciferolond magnesion concentrations in infants with sersures associated with spontaneous hypocalcemia

Se estudio un grupo de doce lactantes con convulsiones asociados a hipocalcemia (5.6 ñ 0.9 mg/dl) y concentraciones inapropiadamente bajas de PTH (1.7 ñ 0.5 ng/ml). En todos los casos, excepto uno el magnesio sérico extuvo 2 DS por abajo del promedio del grupo control (1.7 ng/ml). La concentración promedio de 25 hydroxivitamina D fueron significativamente menores (9.6 ñ 7.1 mg/l) que en los controles (35.2 ñ 15.8 mg.l). Cuatro de los doce lactantes fueron considerados como desnutridos, sus concentraciones de minerales y hormonas fueron comparables a las de los desnutridos hipocalcémicos, excepto las proteínas cuyo promedio fue significante menor (5.4 ñ 0.8 g/dl). Las convulsiones desaparecieron rápidamente después de administrarles una combinación de calcio endovenoso y vitamina D intramuscular. Cuando se les administró magnesio solamente, tanto el calcio cocmo la PTH aumentaron rápidamente. Con base en estos hallazgos se sugiere que la baja concentración de las formas activas de la vitamina D dispararon los mecanismos homeostáticos del metabolismo del calcio. Dando como resultado hipocalcemia debida a la incapacidad de la PTH para responder de manera adecuada al estímulo del calcio. Está incapacidad fue debida a su vez a las bajas concentraciones de magnesio, el cual tiene un papel permisivo en la secreción de PTH