In ayurveda role of Sapta Dhatu is prime in building up the body tissues and digesting food and breaking its essence into 7 different body structure.

When you are dealing with medical astrology one should have thorough understanding on Sapta Dhatu & its reltion with 7 planets.

All the Dhatu's or elements are inter dependent on each other building its preceeding dhatu.

From all Most important is Shukar Dhatu as it is essence of all the 6 dhatus and the Ojas is resultant product of 7 dhatus.

Jyotish is deeply linked with ayurveda to understand diseases pattern in ayurveda astrology.

7 planets linked with 7 dhastus are :

1) Rasa ( Water - Plasma ) - Ruled by the planet Moon and it rules the water element in body and its the kapha which helps to build bodily fluid

When moon is weak it weakens the plasma or bodily fluid movement in women's and http://mens.To  balance it one should maximise the intake of Water or Juices ( Rasa).Remedy related to moon will help to balance the plasma in body.

Intake of Food produces plasma as it contains nutrients and minerals from digested food which nourishes all the tissues and organs.

From Plasma ( Rasa) blood is produced ( Rakta Dhatu), From Blood Mamsa dhatu is produced ( Muscle and flesh ),

from Mamsa it originates Medha dhatu ( Fat) which helps them to build body structure ( bones- Asthma Dhatu).From bone Majja dhatu is produced ( Majja) and further generates Semen or ovum ( Shukra dhatu).

Now when you have to narrow down the diseases pattern via ayurveda astrology one has to find the root cause of the disease.

One should need to understand its root that the food which produces plasma goes into production of blood. RASA ( Moon) is govern by Kapha,

Its the Heart ( Sun) drives the blood and and corruption in the Pitta Dosha ( Malefic Mars - Imbalance in the Jattha agni or pitta ) causes blood disorder ruled by Mars. So Rakta Dhatu is linked with Pitta where role of Both Sun and Mars is important.

Rakta is dependent on Rasa Dhatu which do the work of Nourishment and out of Rakta Dhattu ( Pitta invokement ) it produces the Mamsa dhatu ( Muscle movement) govern by Mars as it governs actions and movement whereas Saturn is responsible for structure of the body.

MAMSA governing Dosha is Kapha as it the do the work of Muscle development.Out of Mamsa meda is produced which is the fat tissues of the body ruled by Jupiter.All the fat in the body is ruled by Meda ( Jupiter role is paramount) as it holds the fat along with water in it.

whereas Kapha is major influencing dosha responsibile for Meda. Out of Meda its produces Asthi Dhatu which is used to build up the bones and body structure. So Role of the Sun is paramount here which helps to build bones.

ASTHI is the main Vata tissue in the body for absorption of prana in the large intestine , both are linked with good digestion and strong bones structure.Its dosha is vata.

From Asthi , Majja ( Nerve or Marrow ) is produced which is further linked with Grey marrow( Nervous system - Mercury ) and red marrow ( Mars required for the bones ). It helps to fill the bones cavity i.e cartilage problem is seen via deficiency of Majja dhatu

Majja Dhatu dominant dosha is Kapha role of Kapha is for nourishment of nerves. From MAJJA dhatu shukra dhatu is formed which is essence of all the dhatu seen for aura, reproduction and charm in the personality ruled by the planet venus ( shukra ).

So Good amount of semen in the body is dependent on good amount of Majja.when Nervous system is good it helps to better produce good quality of semen for reproduction. So Mercury ( Nerves ) are directly linked with venus ( semen) for better quality of shukra dhatu.

Good amount of semen health depends on maximum amount of Kapha in the body which helps to calm the nerves ( Vata) ultimately one will have good sleep and mental health.

Now if you want to diagnose the root cause of disease look for the responsible dhatu and dosha deficiency causing problem in the body.
For e.g if one having Digestion problem the one should look for The Sun as it rules digestion and for digestion one should have balanced pitta

If digestion is weak, it will cause weak bones and it will effect stool.

So to work on digestion and bones one should improve pitta and work on Sun and Jupiter both, as when fat dissolves it produces Asthi Dhatu in body.