Re; The calcium hormones

[Guest guest]

Hi JoAnn (if you're still here),

 

I was looking up " parathyroid " on this site and found some of your

very infomrative articles with the below mentioned from almost

exactly 13 months ago.

 

I've been doing a lot of reading on hyperparathyroidism and how it

takes calcium from the bones. In fact I have a rather high serum

calcium. What surprised me in the article was that calcitrol may not

be the answer. I also suspect that other endocrine glands are

implicated, like insulin and have read that this indeed may be the

case.

 

According to the article, estrogen and now Vitamin K are the good

guys. If you're reading this or anyone else, can you please direct

me to other links where I can get more information?

 

Thanks and regards,

Janet

 

 

 

, JoAnn Guest

<angelprincessjo wrote:

>

> The Calcium-hormones JoAnn Guest Jun 28, 2005 16:53 PDT

 

> The calcium-hormones function like a fire brigade; when

structurally

> little calcium is consumed, they aren't activated that much, which

is

> good ; no fire.

>

> When too much calcium is consumed, the calcium-hormones are very

active,

> stimulating absorption of calcium into the bones, and subsequently

> deportation and excretion. And the more this processed is

enhanced, the

> more the bones erode.

 

> After calcium is absorbed, calcitonine (or thyrocalcitonine)

inhibits

> deportation of calcium from the bones, whilst the calcium

automatically

> keeps pouring in. Calcitonine also stimulates excretion of calcium

> through urinating.

>

> So, calcitonine primarily lowers blood-calcium level, and

absorption of

> calcium into the bones is one way to reach that goal. Absorbing

calcium

> into the bones certainly is not the purpose of calcitonine, for it

> stimulates excretion of calcium too.

>

> Due to the action of calcitonine, the increased blood-calcium

level

> decreases, inhibiting calcitonine release and stimulating

secretion of

> two other calcium-hormones; PTH and calcitriol.

 

> Parathyroid hormone (PTH) stimulates uptake of calcium into the

bones

> (1) (and therefore osteoblast apoptosis (2)) and deportation of

calcium

> from the bones, and inhibits excretion of calcium, generally

increasing

> a low blood-calcium level. Logically, elevated PTH level

accelerates

> ageing of the bones; see hyperparathyroidism

>

> Low levels of PTH prevent bone loss. (3)

>

> PTH also stimulates secretion of calcitriol;

 

> Calcitriol (1,25 dihydroxycholecalciferol = composed of vit. D);

The

> direct influence of calcitriol is increasing the uptake of dietary

> calcium into the blood, but also the uptake of calcium into the

bones

> (4) (Calcitriol therefore also increases osteoblasts apoptosis

(5)) and

> deportation of calcium from the bones.

>

>

>

> Calcitriol however also inhibits secretion of PTH. And since the

> stimulating effect of PTH on the uptake of calcium into the bones

and

> the subsequent deportation, supplementary calcitriol can, per

saldo, in

> fact strongly decrease uptake of calcium into the bones and

subsequent

> deportation. (6) Since calcitriol also increases intestinal

calcium

> absorption, this however also strongly increases blood-calcium

level

> (7).

>

>

>

> Too much calcium in the blood can precipitate in the arteries,

joints

> and ligaments and kills muscle cells (since muscle cells can only

> contract by deporting calcium outside the muscle-cells, which is

harder

> if the blood contains more calcium). Too much calcitriol / vitamin

D can

> cause arteriosclerosis, bone-deformation (8), muscle cramps and

> fibromyalgia.

 

> Estrogen

>

> Estrogens are multi-functional hormones, and one of their

functions

> involves the bones.

>

> The calcium-hormones mentioned above, induce circulation of

calcium;

> from the blood into the bones and vice versa, `pumping' the

calcium

> around. Estrogens are the brakes on this system, to minimize

erosion.

>

>

>

> Calcium is absorbed into the bones due to osteoblasts, which

increase

> free phosphate level in the bones, which causes the `passive'

influx of

> calcium, to restore the calcium-phosphate ratio.

>

> Deportation of calcium from the bones by osteoclasts is an active

> process.

>

 

> Structurally, estrogen does not stimulate osteoblasts (9) , but

even

> inhibits osteoblast activity (10) and therefore inhibits calcium

influx

> in the bones (11) and also inhibits deportation of calcium from

the

> bones. Thus estrogen protects the bones against excessive bone

turnover,

> and osteoblasts against apoptosis.

>

> Estrogen prevents death of osteoblasts in particular because

osteoblasts

> are more sensitive to ageing phenomena than osteoclasts. (12)

 

> In general, this protective effect of estrogen is accredited to

the

> decrease in deportation of calcium from the bones, and is the

inhibitory

> effect of estrogen on calcium influx ignored.

>

> But a characteristic action of estrogens on the skeleton is

inhibition

> of longitudinal bone growth. (13)

>

> Some claim that estrogen increases calcium influx in the bones,

but this

> is only the case in the first 6 days of administration. (9)

 

> The reason why osteoporosis risk in women is higher than in men,

> regardless of menopause and milk consumption, is due to monthly

estrogen and PTH fluctuations;

>

> Estrogen levels in women strongly fluctuate monthly.

>

> As estrogen level is at its lowest (around menstruation), PTH

level is

> at its highest, increasing deportation of calcium from the bones.

(14)

> (and uptake of calcium into the bones)

>

> Thus lifetime bone turnover averagely is higher in women.

 

> Vitamin K

>

> Vitamin K seems to be protective for inhibiting death of

osteoblasts.

> (15) But how exactly this happens, remains unclear; vitamin K may

> inhibit fractional calcium absorption and therefore prevent

osteoblast

> apoptosis. Or vitamin K may reduce `unnecessary' apoptosis of

> osteoblasts even without excessive calcium turnover. Vitamin K can

> however also increase osteoblast apoptosis. (16)

>

> Vitamin K does not affect intestinal calcium absorption (17), but

the

> intake of dietary vitamin K2 has a preventive effect on bone

resorption

> caused by ovariectomie or a lack of vitamin K, and in

postmenopausal

> women.