血脂異常

Dyslipidemia WHO分類:

  type1 chylomicron 高
  type2 LDL
  type3 IDL
  type4 VLDL
  type5 VLDL + chylomicron


膽固醇和三酸甘油脂的來源，
  -一部份是從食物中吸收過來，如食物中的肉類、蛋、和乳類製品都是他們的來源，
  -另一部份則在肝臟中生成，其中膽固醇則由 acetyl-co A 生成。為了評估脂質對於身體的影響及疾病病型的診斷，

乳糜血

  -攝取食物中的油脂先在腸道被消化成小分子，才被腸壁細胞吸收，這些小分子在腸壁細胞中又重新組合並聚合成『乳糜微粒』（Chylomicron），大部分為TG，少部分為膽固醇。
  -乳糜微粒因顆粒大，會產生折光，當濃度高時血漿就會呈現乳白色，稱之為『乳糜血』。嚴重時，甚至血液一抽出來就呈現粉紅色，好像是血液中加入了牛奶。
  -捐血時偶有乳糜血現象者，可能是捐血前的飲食油脂含量較高，且餐後至捐血的時間間隔不夠所致。

  -肝病造成肝臟或脂蛋白分解酶對油脂分解的功能不夠好時，加上攝取過多的油脂或飲酒，就會使乳糜微粒堆積在血液中的時間較長而有乳糜血現象。

脂肪吸收代謝:

  -在小腸形成的乳糜微粒，經由淋巴系統注入血液循環中。

  -乳糜微粒好像是一輛卡車，將從食物所吸收的三酸甘油酯輸送到脂肪組織和肌肉。

  -血液中的乳糜微粒被脂蛋白分解酶分解成脂肪酸和甘油，以供組織細胞利用，剩下的膽固醇與少量的三酸甘油酯則被送到肝臟儲存或代謝。

  -乳糜微粒半衰期很短，數分鐘至數小時內就可被分解，最常見於餐後，正常人隔夜空腹後就不存在。一般而言，餐後血中乳糜微粒濃度會因食物含的脂肪量而增加，約2~4小時達到最高；8~10小時後回復到空腹值。

  

脂蛋白因其比重的不同而可分為五種

    乳糜微滴 (chylomicron)
    極低密度脂蛋白 (VLDL)
    低密度脂蛋白 (LDL)
    中間密度脂蛋白 (intermediate density lipoprotein, IDL)
    高密度脂蛋白 (HDL)

各種脂蛋白的組成

	Chyl	VLDL	IDL	LDL	HDL2	HDL3
電泳	原點	pre-β	β	β	α	α
脂質組成 ﹪
TG	84	50	23	11	5	4
膽固醇	7	19	38	45	22	15
磷脂質	7	18	19	22	30	23
蛋白質	2	8	19	21	41	55

平常我們測定血中下面四項脂質的血中濃度及加上血脂質的電泳分析做為正確評估診斷的依據。

（甲）血脂肪生化測定：

    （一）total cholesterol, Total-C
    （二）high density lipoprotein choesterol, HDL-C
    （三）low density lipoprotein cholesterol, LDL-C
    （四）triglyceride, TG

（乙）血脂質電泳分析： 血脂質的電泳可將血脂質分為四部分：

    （一）α (HDL)
    （二）pre-β (VLDL)
    （三）β (LDL)
    （四）原點（乳糜微滴）

臨床上血脂質蛋白的大致的濃度也可以從1.總膽固醇，2.HDL-C， 3.TG的濃度的測定就可以計算出來。

計算方法如下：

TC = HDL-C + LDL-C + VLDL-C (=TG/5)
VLDL-C=TG/5 = 0.2 x TG
TG=VLDL x5
TG= VLDL (85%) + chylomicron (15%)


不過當三酸甘油脂超過 (400 mg/dl) 時
->VLDL-C = 0.166 (TG) showed equal or improved accuracy with this estimation procedure, particularly at high TG levels.



LDL, chylomicron 高的原因:
 - lipoprotein lipase defi or 異常
 - Apo-C2 出問題

Lipid 代謝:
  - 20-30% 吃入
  - 70-80% 肝製造

Hyper-TG:
  -2° cause 最常見

Hyperchylomicron:
 Ethanol
 Lipoprotein lipase deficiency
 Apolipoprotein C-II deficiency
 T2 DM
 Familial hypertriglyceridaemia


Primary Hyperchylomicronemia

 -a syndrome in which the accumulation of chylomicron occurs in the circulation.

 -The main clinical symptoms are the huge increase in plasma trigriceride and cholesterol, and the presence of xanthomatous eruption, lipemia retinalis, hepatosplenomegaly, and the complication of acute pancreatitis.

 -With gene analysis, a deficiency of lipoproteinlipase (LPL) or apolipoprotein C-II is revealed as a main cause.

 -in some cases, abnormalities of remnant receptors, the presence of antibody against LDL, apolipoprotein C-II, and LDL receptor are reported as causes of chylomicronemia syndrome.

 -the major gene polymorphism and characteristics of clinical symptom of these disease.

-a rare autosomal recessive disease caused by lipoprotein lipase deficiency.

A nine month-old girl presented with eruptive xanthomas revealing a familial hyperchylomicronemia.
No lipoprotein lipase activity was found.
DNA analysis revealed a novel homozygous non-sense mutation of the lipoprotein lipase gene at the codon 288.
The parents were heterozygous carriers.

Familial hyperchylomicronemia usually presents with eruptiva xanthomas, abdominal pain, pancreatic manifestation and lipemia retinalis. Papulo-nodular xanthomas occur more frequently in children as in our case. Eighty lipoprotein lipase gene mutations have been recorded to date. The gene locates on chromosome 8. Only 9 non-sense mutations have been described which lead to a truncated protein. In our case, no enzymatic activity was detected probably due to an absence of secretion of the enzyme, even though catalytic activity persisted. The homozygous carrier status leads to hyperchylomicronemia whereas the heterozygote status may lead to mixed hyperlipidemia with an increased risk of atherosclerosis. The screening of lipoprotein lipase gene mutations should be carried out in all families with hyperchylomicronemia, regardless of the presence or absence of xanthomas.

INTRODUCTION —

 -In many patients hyperlipidemia is caused by some underlying "non-lipid" etiology rather than a primary disorder of lipid metabolism. 

-2° cause of dyslipidemia

• Type 2 DM, poor control
• Cushing synd
• acromegaly
• Excessive alcohol consumption
• Cholestatic liver diseases
• Nephrotic syndrome
• Chronic renal failure
• Hypothyroidism
• Smoking
• Obesity
• Drugs

Fragminham CHD 10-y rsik score (1) score formula, (2) 計算器

Predictors

• Age
• Diabetes
• Smoking
• JNC-V BP categories
• NCEP total cholesterol categories
• LDL cholesterol categories

HyperTG:  Lipanthyl (160mg/#) 1#qd;  ESRD (1# qod)

高血脂症

Lipid disorder from hungchangchen