< Presentation of Case >
A 20-year-old woman was referred to our clinic due to newly diagnosed hypertension with hypokalemia. The patient had been in her usual state of health until 3 months earlier, when she developed malaise and bilateral leg weakness. Her blood pressure was 170/110 mmHg on physical examination. There was no moon face, buffalo hump, central obesity, purple striae, edema, abdominal mass, or bruits. Under the impression of secondary hypertension, serial investigations were performed, which are shown in Table. Laboratory findings revealed hypokalemia (3.0 mEq/L), elevated plasma renin activity (PRA), and increased plasma aldosterone concentration (PAC). Angiography showed patent renal arteries. Magnetic resonance imaging of the abdomen revealed a left renal tumor that had hyperintense signal on T2-weighted image and contrast enhancement in T1 (Figure 1). Bilateral renal venous sampling showed a renin lateralization ratio of 1.76 (left/right). Treatments for her hypertension with 3 categories of agents (alpha blocker, angiotensin receptor blocker and spironolactone) were ineffective to control her hypertension, and she developed nausea and intermittent vomiting with worsening blood pressure control. Further computed tomography-guided biopsy showed renal cortical tumor composed of uniform polygonal cells with occasional peri-nuclear halo, arranged in hemangiopericytic patterns in pathology (Figure 2). The cells were all immunohistochemically positive for actin and negative for cytokeratin and HMB-45, which was compatible with juxtaglomerular cell tumor. She underwent radiofrequency ablation of the renal tumor. Her systolic blood pressure decreased to 100~110 mmHg on the same day without any medical control. Follow-up laboratory examinaitons showed normalization of PRA and serum potassium levels.
< Laboratory data >
1.Results of baseline data
BUN |
CRE |
Na |
K |
ALB |
AST |
ALT |
CK |
mg/dL |
mg/dL |
mmol/L |
mmol/L |
g/dL |
U/L |
U/L |
U/L |
11.4 |
1.3 |
137 |
3.0 |
3.8 |
37 |
32 |
112 |
2.Results of the baseline endocrinologic tests
PRA (ng/ml/hr) |
PAC
(ng/dL) |
1-5 ng/ml/hr |
5-30ng/dL |
38.3 |
96.4 |
***PRA= plasma rennin activity
***PAC= plasma aldosterone concentration
3.Results of PAC and PRA in sampling of the renal veins
|
Left |
Right |
IVC |
Plasma |
Renal vein |
Adrenal vein |
Renal vein |
Adrenal vein |
PAC (ng/dL) |
101.2 |
505.6 |
143.4 |
355 |
191.6 |
39.4 |
PRA (ng/ml/hr) |
20.14 |
7.64 |
11.41 |
30.84 |
9.81 |
8.56 |
*** IVC = inferior vena cava
< 病例解析 >
腎素瘤( reninoma)是源自腎絲球傍細胞的腫瘤(juxtaglomerular cell tumor),會過度分泌腎素(renin),造成血中皮質醛酮濃度(plasma aldosterone concentration, PAC)升高而進一步引起低血鉀及高血壓,是一種可治癒的高血壓疾病。若不及早治療,長期的高血壓會造成器官的損壞;據文獻統計,視網膜病變就達到24%左右,蛋白尿、腎功能不全及左心室肥大則各佔11.3%及7%之多。至於腦中風及腸缺血則較少發生。此病好發在年輕女性。常見的症狀包括年輕型的高血壓及其他頭痛、夜尿、多喝、多尿、倦怠等非專一性的表現。一般在門診檢查針對年輕發病的高血壓併低血鉀,若不如預期 (正常身體因應高血壓時血中皮質醛酮素會降低),皮質醛酮素不降反升,則需要考慮到原發性高皮質醛酮素症( primary aldosteronism )、腎動脈狹窄及腎素瘤的可能性。若血液檢查同時有高腎素 (renin)的表現,則排除掉原發性高皮質醛酮素症,進一步會安排影像學檢查,血管攝影可以排除是否有腎動脈狹窄的可能性。而腹部電腦斷層或磁振攝影可以用來偵測腎臟皮質的病灶,即腎素瘤。最後確診則須作侵入性的腎靜脈抽樣 (renal vein sampling )確定有腫瘤分泌腎素 (renin)。治療以手術去除腫瘤為主,若手術風險大的病人可用放射電燒灼術(radiofrequency ablation)來替代,大部分病人術後高血壓都能有明顯下降或恢復正常。
< 參考文獻 >
- Wong L, et al. Case report and literature review. J Hypertens. 2008 Feb;26(2):368-73.
- Gottardo F, et al. A kidney tumor in an adolescent with severe hypertension and hypokalemia: an uncommon case--case report and review of the literature on reninoma. Urol Int. 2010 Jul;85(1):121-4
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