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Urinary metanephrines in cats : does collection method matter?
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Atualmente, o conhecimento sobre a aplicabilidade clínica do doseamento das metanefrinas em gatos é limitado. A medição de metanefrinas urinárias constitui uma ferramenta de diagnóstico segura e prática para excluir tumores produtores de catecolaminas. Embora a colheita urinária seja habitualmente realizada por cistocentese, a colheita em ambiente doméstico é uma opção menos invasiva, prática e com menor indução de stress. Visto que o stress é uma preocupação em pacientes felinos, é relevante avaliar o impacto do método de colheita nas concentrações urinárias de metanefrinas. Este estudo teve como objetivo comparar os resultados de amostras colhidas em casa e em hospital veterinário por cistocentese. Após aprovação ética, realizou-se um estudo observacional de medidas repetidas com gatos saudáveis ou com doença não adrenal estável, submetidos a ecografia abdominal e exames laboratoriais. Os tutores receberam areia não absorvente e colheram urina em casa antes ou após três dias da cistocentese. As amostras foram refrigeradas a 4 °C no máximo por 24h e depois armazenadas a -80 °C até ao envio para laboratório. Todas as amostras foram analisadas em simultâneo para determinação de metanefrinas e normetanefrinas urinárias (uMN e uNMN, respectivamente) por cromatografia líquida com espectrometria de massa em tandem. A análise estatística foi efetuada com recurso ao software IBM SPSS Statistics. Foram incluídos 19 gatos no estudo. A concentração de uMN livre (mediana [intervalo]) em urina colhida no hospital (690,36 [197,97 – 2228,43] nmol/L) foi significativamente superior à da colhida em casa (324,87 [116,75 – 883,25] nmol/L) (p = 0,003). A concentração de uNMN livre colhida no hospital (1475,41 [475,41 – 5180,33] nmol/L) foi também significativamente superior à da colhida em casa (1267,76 [469,95 – 3459,02] nmol/L) (p = 0,022). O rácio uMN:creatinina na urina colhida no hospital (41 [17 – 154] µg/g) foi significativamente superior ao da urina colhida em casa (26 [9 – 93] µg/g) (p = 0,015). No entanto, os rácios uNMN:creatinina não apresentaram diferenças significativas entre a urina colhida no hospital (85 [44 – 239] µg/g) e em casa (83 [42 – 209] µg/g) (p = 0,481). Estes resultados demonstram que o stress ambiental e consequentemente o método de colheita da urina alteram significativamente as concentrações de uMN livres, de uNMN livres e o rácio uMN:creatinina. No entando, o rácio uNMN:creatinina permanece inalterado, revelando-se um indicador diagnóstico fiável e independente do método de colheita. Após aprovação ética, realizou-se um estudo observacional de medidas repetidas incluindo 19 gatos, saudáveis ou com doença não adrenal estável. Os animais foram submetidos a exame físico completo, ecografia abdominal e exames laboratoriais para excluir doença adrenal. Cada tutor recebeu areia não absorvente (Catrine®) e instruções para recolha de uma amostra de urina em casa, antes ou após três dias da cistocentese hospitalar. As amostras foram refrigeradas a 4 °C por um período máximo de 24 horas, congeladas a 80 °C e posteriormente enviadas em conjunto para análise laboratorial...
Knowledge regarding the clinical applicability of metanephrines in cats is scarce. Urinary metanephrine measurements provide a safe and practical diagnostic tool to rule out catecholamine-producing tumors. While urine collection is usually performed via cystocentesis, urine collection at home is a less invasive option, providing a convenient and stress-free method to collect samples. As stress is always a concern in feline patients, it is essential to assess the impact of sample collection method in metanephrine measurements. This study aims to evaluate potential differences between urinary metanephrines collected at home versus by cystocenthesis in the hospital. After ethical approval, a repeated measures observational study was performed including either healthy cats or cats with stable non-adrenal illness, submitted to an abdominal ultrasound and analytical work-up. Owners were supplied with non-absorbent litter and instructed to either collect urine at home before or at least three days after cystocentesis. Collected samples were refrigerated at 4°C for a maximum of 24h before being stored at -80°C until shipment. All samples were shipped at the same time for urinary metanephrine (uMN) and normetanephrine measurements (uNMN) by liquid chromatography with tandem mass spectrometry. Statistical analysis was preformed using the software IBM SPSS Statistics. Normality was assessed and statistical tests were then chosen accordingly. A total of 19 cats were included. The free uMN concentration (median [range]) in urine collected at the hospital (690.36 [197.97-2228.43] nmol/L) was significantly higher than in urine collected at home (324.87 [116.75-883.25] nmol/L) (p = 0.003). The free uNMN concentration in urine collected at the hospital (1475.41 [475.41-5180.33] nmol/L) was also significantly higher than in the urine collected at home (1267.76 [469.95-3459.02] nmol/L) (p = 0.022). The uMN:creatinine ratio in the urine collected at the hospital (41 [17-154] µg/g) was significantly higher than in the urine collected at home (26 [9-93] µg/g) (p = 0.015). However, the uNMN:creatinine ratios in urine collected at the hospital (85 [44-239] µg/g) and at home (83 [42-209] µg/g) did not differ significantly (p = 0.481). These results show that environmental stress, and consequently the urine collection method, significantly influence free uMN, free uNMN and the uMN:creatinine ratio. However, the uNMN:creatinine ratio remains unchanged, establishing itself as a good diagnostic indicator regardless of collection method
Knowledge regarding the clinical applicability of metanephrines in cats is scarce. Urinary metanephrine measurements provide a safe and practical diagnostic tool to rule out catecholamine-producing tumors. While urine collection is usually performed via cystocentesis, urine collection at home is a less invasive option, providing a convenient and stress-free method to collect samples. As stress is always a concern in feline patients, it is essential to assess the impact of sample collection method in metanephrine measurements. This study aims to evaluate potential differences between urinary metanephrines collected at home versus by cystocenthesis in the hospital. After ethical approval, a repeated measures observational study was performed including either healthy cats or cats with stable non-adrenal illness, submitted to an abdominal ultrasound and analytical work-up. Owners were supplied with non-absorbent litter and instructed to either collect urine at home before or at least three days after cystocentesis. Collected samples were refrigerated at 4°C for a maximum of 24h before being stored at -80°C until shipment. All samples were shipped at the same time for urinary metanephrine (uMN) and normetanephrine measurements (uNMN) by liquid chromatography with tandem mass spectrometry. Statistical analysis was preformed using the software IBM SPSS Statistics. Normality was assessed and statistical tests were then chosen accordingly. A total of 19 cats were included. The free uMN concentration (median [range]) in urine collected at the hospital (690.36 [197.97-2228.43] nmol/L) was significantly higher than in urine collected at home (324.87 [116.75-883.25] nmol/L) (p = 0.003). The free uNMN concentration in urine collected at the hospital (1475.41 [475.41-5180.33] nmol/L) was also significantly higher than in the urine collected at home (1267.76 [469.95-3459.02] nmol/L) (p = 0.022). The uMN:creatinine ratio in the urine collected at the hospital (41 [17-154] µg/g) was significantly higher than in the urine collected at home (26 [9-93] µg/g) (p = 0.015). However, the uNMN:creatinine ratios in urine collected at the hospital (85 [44-239] µg/g) and at home (83 [42-209] µg/g) did not differ significantly (p = 0.481). These results show that environmental stress, and consequently the urine collection method, significantly influence free uMN, free uNMN and the uMN:creatinine ratio. However, the uNMN:creatinine ratio remains unchanged, establishing itself as a good diagnostic indicator regardless of collection method
Descrição
Dissertação de Mestrado Integrado em Medicina Veterinária, área científica de Clínica
Palavras-chave
Urinary metanephrines Urinary normetanephrines Cats Stress Liquid chromatography with tandem mass spectrometry Metanefrinas urinárias Normetanefrinas urinárias Gatos Stress Cromatografia líquida com espectrometria de massa em tandem