Urinary Catecholamine and Metanephrine to Creatinine Ratios in Dogs with Hyperadrenocorticism or Pheochromocytoma, and in Healthy Dogs

Abstract

Background: Urinary catecholamines and metanephrines are used for the diagnosis of pheochromocytoma (PHEO) in dogs. Hyperadrenocorticism (HAC) is an important differential diagnosis for PHEO.Objectives: To measure urinary catecholamines and metanephrines in dogs with HAC. Animals: Fourteen dogs with HAC, 7 dogs with PHEO, and 10 healthy dogs. Methods: Prospective clinical trial. Urine was collected during initial work-up in the hospital; in dogs with HAC an additional sample was taken at home 1 week after discharge. Parameters were measured using high-pressure liquid chromatography and expressed as ratios to urinary creatinine concentration.Results: Dogs with HAC had significantly higher urinary epinephrine, norepinephrine and normetanephrine to creatinine ratios than healthy dogs. Urinary epinephrine, norepinephrine, and metanephrine to creatinine ratios did not differ between dogs with HAC and dogs with PHEO, whereas the urinary normetanephrine to creatinine ratio was significantly higher (P 5 .011) in dogs with PHEO (414, median, range versus (117.5,. Using a cut-off ratio of 4 times the highest normetanephrine to creatinine ratio measured in controls, there was no overlap between dogs with HAC and dogs with PHEO. The variables determined in urine samples collected at home did not differ from those collected in the hospital.Conclusion and Clinical Importance: Dogs with HAC might have increased concentrations of urinary catecholamines and normetanephrine. A high concentration of urinary normetanephrine (4 times normal), is highly suggestive of PHEO.

Clinical features, outcome and prognostic factors in dogs diagnosed with non‐cortisol‐secreting adrenal tumours without adrenalectomy: 20 cases (1994–2009)

“…Pheocromocytomas are generally not suspected antemortem and tend to be malignant in nature (Kyles and others 2003, Herrera and others 2008, Lang and others 2011). When clinical signs are observed, they result from the excessive secretion of catecholamines; some of these clinical signs are depression, panting, weakness, tachycardia and polyuria/polydipsia (Quante and others 2010). These tumours can be diagnosed by measuring the urinary catecholamines and metanephrines to creatinine ratios, or measuring plasma-free normetanephrine, although some of these tests lack the adequate sensitivity and specificity, are not widely available for clinicians or validated for its use in dogs (Quante and others 2010, Gostelow and others 2013).…”

“…As it is described, adrenal adenomas usually are slow growing tumours (Capen 2002), so dogs with hypertension could be more likely to have a carcinoma. It could also be possible, that animals with a higher diastolic blood pressure could have been those with clinically unapparent pheocromocytomas, or even aldosteronoma, as hypertension is one of the common clinical signs of animals with these types of tumours (Herrera and others 2008, Quante and others 2010, Melián 2012). As mentioned before, sometimes the diagnosis of these tumours is difficult, and when pheocromocytomas or primary hyperaldosteronism cannot be ruled out, diastolic pressure could be used as a tool for predicting tumour growth and for making the decision whether to perform adrenalectomy or not.…”

Adrenal gland tumours. Different clinical presentations in three dogs: a case report

“…Hypercholesterolaemia can occur secondary to catecholamine-induced lipolysis and subsequent conversion of fatty acids in the liver (Gilson et al 1994). Moreover, the clinical signs, weakness, episodic collapse, tachypnoea, panting, tachycardia, pacing, polyuria, polydipsia, hypertension, vomiting and diarrhoea, and diagnostic test interpretation are vague and non-specific, making diagnosis challenging (Kook et al 2007Quante et al 2010). In humans, the diagnosis of a pheochromocytoma is based mainly on biochemical detection of excessive production of the secretory products of the tumours.…”

Pheochromocytoma

“…1 Pheochromocytomas may also secrete hormones such as vasoactive intestinal peptide, which can contribute to clinical signs such as diarrhea. 7,29 One study showed that dogs with hyperadrenocorticism had increased concentrations of urinary catecholamines and normetanephine compared with normal dogs, and a high (four times normal) concentration of urinary normetanephrine was highly suggestive of pheochromocytoma. 7,8 In 20 dogs with a pheochromocytoma but without concurrent disease, 50% showed proteinuria, likely caused by a hypertensive glomerulopathy.…”

“…In two retrospective reports of dogs with pheochromocytoma, hypercholesterolemia was present in 25% of dogs, possibly secondary to increased fat mobilization from catecholamine secretion or because of concurrent hyperadrenocorticism. 29 Secondary factors, such as excitement, exercise, vanilla-containing foods, phenoxybenzamine therapy, and radiographic contrast agents may result in false-positive elevations. 2 Measurement of urinary catecholamine concentrations (metanephrine, normetanephrine, vanillylmandelic acid) as a spot check referenced to urine creatinine, or over a 24-hour period, is performed in humans with suspected pheochromocytomas and has been investigated in dogs.…”