Hypoparathyroidism

Hypoparathyroidism is a condition of reduced or absent PTH secretion, resulting in hypocalcaemia and hyperphosphataemia. It is far less common than hyperparathyroidism.

The causes of hypoparathyroidism are:
- Removal or damage of the parathyroid glands during thyroidectomy—most common cause of hypoparathyroidism resulting from inadvertent damage or removal.
- Autoimmune parathyroid disease—usually occurs in patients who have another autoimmune endocrine disease, e.g. Addison’s disease (autoimmune endocrine syndrome type 1).
- Congenital deficiency (DiGeorge syndrome)— rare, congenital disorder caused by arrested development of the third and fourth branchial arches, resulting in an almost complete absence of the thymus and parathyroid gland.

The effects of hypoparathyroidism are:
- ↓ release of Ca²⁺ from bones. 
- ↓ Ca²⁺ reabsorption but ↑ PO ₄³⁻ re absorption by the kidneys
- ↓ 1-hydroxylation of 25-hydroxyvitamin D by kidney.

Most symptoms of hypoparathyroidism are those of hypocalcaemia:
- Tetany—muscular spasm provoked by lowered plasma Ca 2+ 
- Convulsions.
- Paraesthesiae.
- Psychiatric disturbances, e.g. depression, confusional state and even psychosis.
- Rarely—cataracts, parkinsonian-like movement disorders, alopecia, brittle nails.

Management is by treatment with large doses of oral vitamin D; the acute phase requires intravenous calcium and calcitriol (1,25-dihydroxycholecalciferol, i.e.  activated vitamin D).

Hepatic failure 
Etiology. Chronic hepatic disease (e.g., chronic active hepatitis or alcoholic cirrhosis) is the most common cause of hepatic failure although acute liver disease may also be responsible.

- Widespread liver necrosis may be seen with carbon tetrachloride and acetaminophen toxicity. Widespread steatosis is seen in Reye's syndrome, a cause of acute liver failure most often seen in children with a recent history of aspirin ingestion for an unrelated viral illness. 
- Massive necrosis may also be seen in acute viral hepatitis, after certain anesthetic agents, and in shock from any cause. 

Clinical features. Hepatic failure causes jaundice, musty odor of breath and urine, encephalopathy, renal failure (either by simultaneous toxicity to the liver and kidneys or the hepatorerial syndrome), palmar erythema, spider angiomas, gynecomastia , testicular atrophy 

HAEMORRHAGIC DISORDERS

Normal homeostasis depends on

 -Capillary integrity and tissue support.

- Platelets; number and function

(a) For integrity of capillary endothelium and platelet plug by adhesion and aggregation

(b) Vasoactive substances for vasoconstriction

(c) Platelet factor for coagulation.

(d) clot retraction.

- Fibrinolytic system(mainly Plasmin) : which keeps the coagulatian system in check.

Coagulation disorders

These may be factors :

Deficiency .of factors

• Genetic.
• Vitamin K deficiency.
• Liver disease.
• Secondary to disseminated intravascular coagulation.or defibrinatian

Overactive fibrinolytic system.

Inhibitors of  the factars (immune, acquired).

Anticoagulant therapy as in myocardial infarctian.

Haemophilia. Genetic disease transmitted as X linked recessive trait. Comman in Europe. Defect in fcatorVII  Haemophilia A .or in fact .or IX-Haemaphilia B (rarer).

Features:

• May manifest in infancy or later.
• Severity depends  on degree of deficiency.
• Persistant woundbleeding.
• Easy Bruising with Haemotoma formation

Nose bleed , arthrosis, abdominal pain with fever and leucocytosis

Prognosis is good with prevention of trauma and-transfusion of Fresh blood or fTesh plasma except for danger of developing immune inhibitors.

Von Willebrand's disease. Capillary fragility and decreased factor VIII (due to deficient stimulatory factor). It is transmitted in an autosomal dominant manner both. Sexes affected equally

Vitamin K  Deficiency. Vitamin K is needed for synthesis of factor II,VII,IX and X.

Deficiency maybe due to:

Obstructive jaundice.

Steatorrhoea.

Gut sterilisation by antibiotics.

Liver disease results in :

Deficient synthesis of factor I II, V, Vll, IX and X  Incseased fibrinolysis (as liver is the site of detoxification of activators ).

Defibrination syndrome. occurs when factors are depleted due to disseminated .intravascular coagulation (DIC). It is initiated by endothelial damage or tissue factor entering the circulation.

Causes

Obstetric accidents, especially amniotic fluid embolism. Septicaemia. .

Hypersensitivity reactions.

Disseminated malignancy.

Snake bite.

Vascular defects :

(Non thrombocytopenic purpura).

Acquired :

Simple purpura a seen in women. It is probably endocrinal

Senile parpura in old people due to reduced tissue support to vessels

Allergic or toxic damage to endothelium due to  Infections like Typhoid Septicemia

Col!agen diseases.

Scurvy

Uraemia damage to  endothelium (platelet defects).

Drugs like aspirin. tranquillisers, Streptomvcin pencillin etc.

Henoc schonlien purpura Widespeard vasculitis due to hypersensitivity to bacteria or foodstuff

It manifests as :

Pulrpurric rashes.

Arthralgia.

Abdominal pain.

Nephritis and haematuria.

Hereditary :

(a) Haemhoragic telangieclasia. Spider like tortous vessels which bleed easily. There are disseminated lesions in skin, mucosa and viscera.

(b) Hereditary capillary fragilily similar to the vascular component of von Willbrand’s disease

.(c) Ehler Danlos Syndrome which is a connective tissue defect with skin, vascular and joint manifestations.

Platelet defects

These may be :

(I) Qualitative thromboasthenia and thrombocytopathy.

(2) Thrombocytopenia :Reduction in number.

(a) Primary or idiopathic thrombocytopenic purpura.

(b) Secondary to :

(i) Drugs especially sedormid

(ii) Leukaemias

(iii) Aplastic-anaemia.

Idiopathic thrombocytopenic purpura (ITP). Commoner in young females.

Manifests as :

Acute self limiting type.

Chronic recurring type.

Features:

(i) Spontaneous bleeding and easy bruisability

(ii)Skin (petechiae), mucus membrane (epistaxis) lesions and sometimes visceral lesions involving any organ.

Thrombocytopenia with abnormal forms of platelets.

Marrow shows increased megakaryocytes with immature forms,

vacuolation, and lack of platelet budding.

Pathogenesis:

hypersensitivity to infective agent in acute type.

Plasma thrombocytopenic factor ( Antibody in nature) in chronic type

INFLUENZA

An acute viral respiratory infection with influenza, a virus causing fever, coryza, cough, headache, malaise, and inflamed respiratory mucous membranes.

Influenza B viruses typically cause mild respiratory disease

Symptoms and Signs

mild cases:

Chills and fever up to 39 to 39.5° C

Prostration and generalized aches and pains, Headache, photophobia and retrobulbar aching

Respiratory tract symptoms may be mild at first, with scratchy sore throat, substernal burning, nonproductive cough, and sometimes coryza. Later, the lower respiratory illness becomes dominant; cough can be persistent and productive.

severe cases

sputum may be bloody. Skin is warm and flushed. Soft palate, posterior hard palate, tonsillar pillars, and posterior pharyngeal wall may be reddened, but no exudate appears. Eyes water easily, and the conjunctiva may be mildly inflamed

Encephalitis, myocarditis, and myoglobinuria are infrequent complications of influenza and, if present, usually occur during convalescence

Nevus

A nevus refers to any congenital lesion of the skin, while a nevocellular nevus specifically refers to a benign tumor of neural crest-derived cells that include modified melanocytes of various shapes (nevus cells).
 - nevocellular nevi are generally tan to deep brown, uniformly pigmented, small papules with well-defined, rounded borders.
 - most nevocellular nevi are subdivided into junctional, intradermal, or compound types.
 - most nevocellular nevi begin as junctional nevi with nevus cells located along the basal cell layer producing small, flat lesions, which are only slightly raised. 
- junctional nevi usually develop into compound nevi as nevus cells extend into the underlying superficial dermis forming cords and columns of cells (compound: nevi at junction and in the dermis).
 - eventually, the junctional component of a nevocellular nevus is lost, leaving only nevus cells within the dermis, thus the term intradermal nevus.
 - junctional → compound → intradermal nevus.
 - although uncommon, certain nevi may evolve into a malignant melanoma, particularly those which are congenital and those which are referred to as dysplastic nevi.
 - a dysplastic nevus is commonly associated with patients who have multiple scattered nevi over the entire body (dysplastic nevus syndrome) with individual lesions that have a diameter greater than 1 cm.

Psoriasis
1. Characterized by skin lesions that appear as scaly, white plaques.
2. Caused by rapid proliferation of the epidermis.
3. Autoimmune pathogenesis; exact mechanism is unclear.