Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0037315 (sleep apnea)
 8,000 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ambulatory blood pressure monitoring can determine the average blood pressure level and the short- and long-term blood pressure variability (circadian rhythm). The circadian blood pressure rhythm appears to be mediated mainly by the circadian rhythm of the sympathetic tone which is linked to changes in physical and mental activity, e.g. the waking-sleeping cycle. A statistically significant circadian blood pressure rhythm was observed in approximately 80% of mild to moderate essential hypertensive patients as well as in normal subjects. However, in patients with Cushing's syndrome, under glucocorticoid treatment, or with hyperthyroidism, central and/or peripheral autonomic dysfunction (Shy-Drager syndrome, spinal cord injury, brainstem lesions, diabetic neuropathy, uremic neuropathy, etc), chronic renal failure, eclampsia, malignant hypertension, sleep apnea syndrome or systemic atherosclerosis, the normal circadian blood pressure rhythm appears to be eliminated or reversed, while in those with primary aldosteronism, renovascular hypertension, pheochromocytoma without paroxysmal hypertension, diabetes insipidus, acromegaly, hyperparathyroidism or hyperprolactinemia, the nocturnal blood pressure fall has been observed as in normal subjects. The alteration in the circadian blood pressure rhythm was observed with different pathophysiological conditions, although no specific pattern was observed for any condition. A disturbance in any part of the hierarchy of factors that regulate the circadian rhythm of sympathetic neural tone seems to disturb the circadian blood pressure rhythm. We conclude that ambulatory blood pressure monitoring is not critically important in the diagnosis of secondary hypertension although it does help in screening for secondary hypertension.
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PMID:Does ambulatory blood pressure monitoring improve the diagnosis of secondary hypertension? 208 1

The daily variation in blood pressure (circadian blood pressure rhythm) is characterized by a nocturnal fall and a diurnal rise. The circadian blood pressure rhythm seems to be mediated mainly by the circadian rhythm of sympathetic tone, linked to changes in physical and mental activities, e.g. the waking-sleeping cycle. Statistically significant circadian blood pressure rhythms have been confirmed in approximately 80% of mild to moderate essential hypertensive patients as well as in normal subjects. However, the normal pattern of circadian blood pressure rhythm is reversed in elderly people and in those with Cushing's syndrome, those undergoing glucocorticoid treatment, and those with hyperthyroidism, central and/or peripheral autonomic dysfunction (Shy-Drager syndrome, tetraplegia, diabetic or uremic neuropathy, etc), chronic renal failure, renal or cardiac transplantation, congestive heart failure, eclampsia, sleep apnea syndrome, malignant hypertension, systemic atherosclerosis and accelerated hypertensive organ damage. However, in those with primary aldosteronism, renovascular hypertension, pheochromocytoma without paroxysmal hypertension, or those with cardiac pacing, a nocturnal blood pressure fall is ordinarily observed. It may be that a fall in cardiac output rather than in peripheral resistance may be mainly responsible for the nocturnal fall in blood pressure. It also seems that a nocturnal heart rate fall is not responsible for it, since the nocturnal blood pressure fall remained unchanged in patients undergoing cardiac pacing and was disturbed in patients with Cushing's syndrome or hyperthyroidism in whom the circadian heart rate rhythm remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Circadian blood pressure variations under different pathophysiological conditions. 209 80

A less-than-normal decline in nocturnal blood pressure (BP) has been associated with excessive hypertensive complications. This is concerning because secondary hypertension is often associated with this so-called nondipper BP profile. A nondipping pattern is more frequently found in the presence of pheochromocytoma, Cushing's syndrome, and sleep apnea syndrome, but the prevalence is unclear in patients with primary hyperaldosteronism. We therefore studied ambulatory BP profiles in 16 hypertensive patients with primary hyperaldosteronism and an equal number of essential hypertensive subjects. The awake-sleep BP difference of the hyperaldosteronism patients was similar to that of essential hypertensives (15/14 +/- 3/2 versus 14/9 +/- 3/2 mm Hg, P=NS). The prevalence of dippers and nondippers (according to two distinct criteria) in the two groups was similar. Repeat ambulatory BP monitoring in 12 subjects with primary hyperaldosteronism after specific intervention (3 after surgical removal of an adrenal adenoma and 9 after commencement and titration of spironolactone therapy) showed highly significant reductions in office BP (22/10 +/- 6/4 mm Hg, P<.05) and awake and sleep BP. However, the extent of nocturnal BP decline was unchanged between the two studies (17/16 +/- 3/3 versus 16/12 +/- 2/2 mm Hg, P=NS). There was no correlation between the awake-sleep difference and serum or urinary aldosterone levels or the aldosterone-to-renin ratio. In this study, we did not detect any differences in the awake-sleep differences between a group of hypertensives with primary hyperaldosteronism and a control group of essential hypertensives.
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PMID:Circadian blood pressure variation in hypertensive patients with primary hyperaldosteronism. 949 70

The treacherous and deceptive nature of pheochromocytoma makes it crucial to detect and treat it promptly; otherwise it will almost certainly be fatal from cardiovascular complications or metastases. Hypertension occurring in patients with pheochromocytomas is sustained in about 50% and paroxysmal in the remainder; however, many patients remain normotensive. Hypertension attacks may be precipitated by physical activity, postural changes, anxiety, certain foods or wine, some drugs, operative procedures, etc. Cardinal manifestations are paroxysmal hypertension, headache, palpitations +/- tachycardia, inappropriate sweating; anxiety, tremulousness, pallor (rarely flushing), chest and abdominal pains; nausea and vomiting often occur. Hypercatecholaminemia manifestations are more common and pronounced when paroxysmal hypertension occurs, but persons with familial pheochromocytoma may be asymptomatic. Protean manifestations of pheochromocytoma may simulate many conditions, some of which may have elevated plasma and urine catecholamines and their metabolites. Baro-reflex failure, postural tachycardia syndrome, sleep apnea, carcinoid, renal failure, and pseudopheochromocytoma may be diagnostic challenges. The history, physical examination, biochemical testing (after eliminating interfering drugs, when possible) for plasma and urinary metanephrines can usually establish or exclude presence of pheochromocytomas. Occasionally a clonidine suppression test is needed to differentiate neurogenic from pheochromocytic hypertension. Manifestations suggesting hypercatecholaminemia without hypertension are highly atypical of pheochromocytoma. Pheochromocytoma may present as panic attacks, pre-eclampsia, cardiomyopathy, infection with fever and leucocytosis, diabetes, migraine, shock, Cushing's syndrome, multiple organ failure with lactic acidosis, neurological manifestations, transitory electrocardiogram abnormalities, constipation, intestinal obstruction, visual impairment, convulsions, etc. The key to diagnosis is always to think of pheochromocytoma in the differential diagnosis of hypertension.
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PMID:The protean manifestations of pheochromocytoma. 1924 99

A 39-year-old man with a history of poorly controlled hypertension presented with a 2-year history of fatigue, daytime somnolence, and intermittent episodes of diaphoresis and palpitations. Episodes were self-limiting, lasting approximately 5-10 minutes and occurred several times per month, most notably at night. Laboratory evaluation was significant for elevated 24-h urinary catecholamine levels, suggestive of pheochromocytoma. However, thorough imaging failed to identify a catecholamine-secreting tumor. Subsequent polysomnography revealed severe obstructive sleep apnea, with an apnea-hypopnea index of 112 events/h. After one month of continuous positive airway pressure therapy, the patient experienced resolution of his presenting symptoms, improved blood pressure control and normalization of his urinary catecholamine levels. This case highlights sleep disordered breathing as a potentially reversible cause of pseudopheochromocytoma.
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PMID:Obstructive sleep apnea presenting as pseudopheochromocytoma. 2041 98

Intermittent hypoxia (IH) associated with sleep apnea leads to cardio-respiratory morbidities. Previous studies have shown that IH alters the synthesis of neurotransmitters including catecholamines and neuropeptides in brainstem regions associated with regulation of cardio-respiratory functions. GABA, a major inhibitory neurotransmitter in the CNS, has been implicated in cardio-respiratory control. GABA synthesis is primarily catalyzed by glutamic acid decarboxylase (GAD). In this study, we tested the hypothesis that IH like its effect on other transmitters also alters GABA synthesis. The impact of IH on GABA synthesis was investigated in pheochromocytoma 12 cells, a neuronal cell line which is known to express active form of GAD67 in the cytosolic fraction and also assessed the underlying mechanisms contributing to IH-evoked response. Exposure of cell cultures to IH decreased GAD67 activity and GABA level. IH-evoked decrease in GAD67 activity was caused by increased cAMP - protein kinase A (PKA) - dependent phosphorylation of GAD67, but not as a result of changes in either GAD67 mRNA or protein expression. PKA inhibitor restored GAD67 activity and GABA levels in IH treated cells. Pheochromocytoma 12 cells express dopamine 1 receptor (D1R), a G-protein coupled receptor whose activation increased adenylyl cyclase activity. Treatment with either D1R antagonist or adenylyl cyclase inhibitor reversed IH-evoked GAD67 inhibition. Silencing D1R expression with siRNA reversed cAMP elevation and GAD67 inhibition by IH. These results provide evidence for the role of D1R-cAMP-PKA signaling in IH-mediated inhibition of GAD67 via protein phosphorylation resulting in down-regulation of GABA synthesis.
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PMID:Post-translational modification of glutamic acid decarboxylase 67 by intermittent hypoxia: evidence for the involvement of dopamine D1 receptor signaling. 2096 67

Evidence for treatment of hypertension in older people is limited to placebo-controlled studies that reduced blood pressure in persons over 60 years who had systolic blood pressure >160 mmHg. Generally, physicians measure blood pressure poorly, failing to look for white coat or masked hypertension, orthostasis, postprandial hypotension, or pseudohypertension. There is evidence that if 24-hour ambulatory blood pressures were obtained, the treatment goal should be substantially lower. Sleep apnea, pain, nocturnal hypoglycemia, drugs, excess aldosterone production, and pheochromocytoma should all be considered as causes of hypertension in older persons. Evidence supports a low-dose diuretic or an angiotensin converting enzyme inhibitor as appropriate first-line therapies in older persons.
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PMID:Treatment of hypertension in older persons: what is the evidence? 2466 34

This article discusses headaches secondary to disorders of homeostasis, which include headaches attributed to (1) hypoxia and/or hypercapnia (high-altitude, diving, or sleep apnea), (2) dialysis, (3) arterial hypertension (pheochromocytoma, hypertensive crisis without hypertensive encephalopathy, hypertensive encephalopathy, preeclampsia or eclampsia, or autonomic dysreflexia), (4) hypothyroidism, (5) fasting, (6) cardiac cephalalgia, and (7) other disorder of homeostasis. Clinical features and diagnosis as well as therapeutic strategies are discussed for each headache type.
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PMID:Metabolic headaches. 2470 39

Context. As catecholamine elevation is a key element in the diagnosis of pheochromocytoma, more commonplace causes of sympathetic excess, such as obstructive sleep apnea (OSA), should be excluded as standard practice prior to diagnosis. This is essential to avoid misdiagnosis of adrenal incidentalomas identified in the estimated 42 million Americans with OSA, with greater than 4 million projected to undergo a computed tomography study annually. Case Description. A 56-year-old woman presented with a several year history of paroxysmal hypertension, palpitations, and diaphoresis. Abdominal/pelvic computed tomography performed during an unrelated hospitalization revealed a 2-cm left-sided adrenal nodule initially quantified at 37 Hounsfield units. Posthospitalization, 24-hour urine normetanephrine level was markedly elevated. Reassessment 2 weeks later revealed continued normetanephrine excess. Following normal thyroid function tests, morning cortisol, aldosterone, and plasma renin activity, laparoscopic adrenalectomy was performed. Surgical pathology identified an adrenal cortical adenoma. As paroxysms continued postoperatively, repeat 24-hour urine metanephrines were measured, demonstrating essentially unchanged normetanephrine elevation. Search for an alternate cause ensued, revealing OSA with progressive continuous positive airway pressure noncompliance over the preceding year. Regular continuous positive airway pressure therapy was resumed, and at the end of 7 weeks, 24-hour urine normetanephrine levels had declined. Conclusion. Pheochromocytomas are rare and sleep apnea is common. However, the overlap of clinical symptoms between these disorders is substantial, as is their ability to produce catecholamine excess. Thus, excluding uncontrolled or undiagnosed OSA in high-risk patients should be standard practice before diagnosing pheochromocytoma.
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PMID:The Importance of Exclusion of Obstructive Sleep Apnea During Screening for Adrenal Adenoma and Diagnosis of Pheochromocytoma. 2690 4

A 52-year-old female with a history of poorly controlled resistant hypertension was admitted to our hospital with severe hypertension. She had a history of fatigue and intermittent episodes of palpitations. Laboratory evaluation was significant for elevated 24-h urinary catecholamine levels (3,5 times the upper normal levels). This case was presenting with a clinical and biochemical picture indistinguishable from that of pheochromocytoma. However, neither computed tomography nor meta-iodo-benzyl-guanidine scintigraphy detected any catecholamine-producing tumor in or outside the adrenal glands. Our patient was screened with full polysomnography because of heavy snoring, daytime somnolence and obesity. It revealed severe obstructive sleep apnea syndrome. After three months of continuous positive airway pressure therapy, the patient experienced resolution of his presenting symptoms, improved blood pressure control and normalization of his urinary catecholamine levels. This case highlights sleep disordered breathing as a potentially reversible cause of pseudo-pheochromocytoma.
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PMID:Obstructive sleep apnea presenting as pseudopheochromocytoma. 2721 98


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