What does low cholesterol mean?

I donate blood regularly and while it's always been rather low (never above 160), it's dropped off even more recently and stabilized around 120. Obviously they only measure total cholesterol, so I don't know LDL and HDL measurements. Worth asking my doctor about? What are the implications? It's definitely not a matter of not eating enough.
Answers:
Cholesterol is a waxy fat like substance that is important for normal body functioning. Cholesterol is used for cellular functions and the production of hormones. Your body, in most cases, will produce enough cholesterol to maintain normal body needs. The liver is the major production factory for cholesterol (about 70%). Diets high in saturated fats, significantly increase the amount of cholesterol in the blood stream. Recommended daily intake of fat should not exceed 30% of calories, with a maximum of 10% being from saturated fat. Research indicates that diets high in saturated and total fat, play a significant role in the process of atherosclerosis (plaque build-up on the artery wall ).High cholesterol levels are strong indicators of those individuals that are prone to coronary heart disease. Elevated total cholesterol is a risk factor for coronary heart disease. The build-up of plaque in the artery may lead to narrowing (high blood pressure) or complete blockage (heart attack) of the vessel. As levels rise above 180 mg/dl, the risk for developing coronary heart disease increases. A cholesterol value of 220 mg/dl correlates to nearly a two-fold elevation in incidence of coronary heart disease as compared to 180 mg/dl. A reduction of 1% is shown to reduce the risk for coronary artery disease by 2% for levels over 200 mg/dl.Total cholesterol is the sum of all the cholesterol in your blood. The higher your total cholesterol, the greater your risk for heart disease. Here are the total values that matter to you. Total Cholesterol Levels:

Less than 200 mg/dL "Desirable" level that puts you at lower risk for heart disease. A cholesterol level of 200 mg/dL or greater increases your risk. 200 to 239 mg/dL "Borderline-high." 240 mg/dL and above "High" blood cholesterol. A person with this level has more than twice the risk of heart disease compared to someone whose cholesterol is below 200 mg/dL.
LDL or Low density LipoProtein(Bad cholesterol) - distibute fatty deposite on vessel wall thus promotes the formation of atherosclorotic plaque.
HDL or High Density LipoProtein(Good Cholesterol) -collects fatty deposites on vessel wall and transport to liver for bile synthesis or other metabolic activity. On this process it prevents or retards the formation of atherosclorosis. Normal Levels:
Desirable total cholesterol: below 200 mg/dL (5.17 mmol/L)
Optimal LDL ('bad') cholesterol: below 100 mg/dL (2.6 mmol/L)
Optimal HDL ('good') cholesterol: over 60 mg/dL (1.56 mmol/L)
Conclusion:
You have a LOW TOTAL CHOLESTEROL level of 120 mg/dl
Implication:
You are less prone to develop Coronary Artery Diseases. Good for you and keep up the healthy living.

---

Abnormally low levels of cholesterol are termed hypocholesterolemia. Research into the causes of this state is relatively limited, and while some studies suggest a link with depression, cancer and cerebral hemorrhage it is unclear whether the low cholesterol levels are a cause for these conditions or an epiphenomenon

---

Well, when i asked my doc. about a blood test that i did that had something low on it that i did not know what it was, he sad: "well that thing u have low, it's kinda the family of cholesterol. so if u have it low, it's a very VERY VERY good thing." So i guess it's the same with cholesterol.

---