Challenges and anxiety of fluctuating normal to mild/moderate elevations of urinary catecholamines and metanephrines in clinical practice

Bonnie Grant; Mohammadreza Emami; Siraj Adam; Edel Casey; Raj Tanday; Anna Hawkins; Nemanja Stojanovic; Imran Syed; Khash Nikookam

doi:10.1530/endoabs.81.P540

We present a 70-year-old female who was initially referred to the endocrinology clinic for an assessment of her type 2 diabetes mellitus. She has a complex medical history including treated hypothyroidism, mastectomy for breast cancer and ongoing yearly surveillance for an excised benign lung lesion. On further questioning she acknowledged feeling generally unwell in the days prior to her appointment and had self-presented to the emergency department with undiagnosed hypertension (blood pressure 219/110mmHg and 190/80mmHg) but no evidence of end-organ hypertensive damage. A full clinical examination did not identify either endocrinopathies or any cardiovascular abnormalities. She was commenced on amlodipine 5 mg daily and subsequently ramipril 5 mg daily. Given her severe hypertension and a negative family history for the same, urinary catecholamines and metanephrines in addition to renin/aldosterone ratio and other relevant investigations were performed to exclude secondary causes. Table 1 shows results performed on three separate occasions, each four weeks apart. She was commenced on doxazosin 1 mg twice daily while also recommended to stop ramipril; however, she was unable to tolerate this nor a switch to phenoxybenzamine 10 mg twice daily, with debilitating side effects of palpitations and dizziness. A CT adrenal with contrast showed no adrenal nodularity bilaterally suspicious of phaeochromocytomas. Further evaluation with I-123 MIBG Scintigraphy and Ga-68 DOTATATE was also negative for any MIBG or DOTATATE avid lesions. The patient continued amlodipine 5 mg daily, achieving adequate blood pressure control with a systolic range of 125-130mmHg and diastolic range of 62-75mmHg. 24-hour urinary catecholamines were repeated six months later, shown in table 2. The patient was advised to further follow up in the endocrine clinic and regular monitoring with her General Practitioner. In conclusion, this case highlights the challenges we encounter during clinical practice with fluctuating urinary catecholamines and metanephrines when other causes of hypertension have been excluded. This can cause additional anxiety over the underlying diagnosis to both the clinician and the patient.

Table 1 24-hour urinary catecholamines and metanephrines. RR=Reference Range.
	Metadrenaline (RR <1.2μmols/24hr)		Normetadrenaline (RR <3.3μmols/24hr)		3-Methoxytyramine (RR <2.5μmols/24hr)
First urine collection	0.25		2.81		0.82
	Metanephrines (RR <1622 nmol/24hr)	Normetanephrines (RR <2129 nmol/24hr)	3-Methoxytyramine (RR <2300 nmol/24hr)	Adrenaline (RR <147 nmol/24hr)	Noradrenaline (RR <573 nmol/24hr)	Dopamine (RR <3270 nmol/24hr)
Second urine collection	346	3990	1769	30	681	-
Third urine collection	334	3380	1459	19	527	1950

Table 2 Repeat 24-hour urinary metanephrines
Metadrenaline (RR <1.2μmols/24hr)	Normetadrenaline (RR<3.3μmols/24hr)	3-Methoxytyramine (RR<2.5μmols/24hr)
0.38	2.66	1.41

Endocrine Abstracts

P540