Phenylketonuria (PKU): Symptoms, Causes, Diagnosis, Treatment & Low-Phenylalanine Diet Guide

Phenylketonuria (PKU): Symptoms, Causes, Diagnosis, Treatment & Low-Phenylalanine Diet Guide

pediagenosis    August 07, 2026   

 

NORMAL AND ABNORMAL METABOLISM OF PHENYLALANINE

         PHENYLKETONURIA

Phenylalanine is an essential amino acid that serves as a substrate for many different biochemical pathways. Two end products that use phenylalanine as their precursors are melanin and epinephrine. Under normal physiological and biochemical environments, any excess amount of phenylalanine is converted into tyrosine by the liver and used for a host of biochemical processes including protein synthesis. In patients with phenylketonuria, the enzyme in the liver that converts phenylalanine into tyrosine is completely absent. This inborn error of metabolism is one of the most thoroughly researched disease states. With early detection and therapy, the severe sequelae of phenylketonuria can be avoided. Screening is performed soon after birth for all children in the United States and in most of the world. Children born in regions with poor medical infrastructure and no testing are at risk for the disease. Once the disease symptoms have appeared, therapy usually cannot reverse the damage that has been done. Phenyl-ketonuria is inherited in an autosomal recessive manner, but many genotypes have been described, and many mutations in the responsible gene have been reported. The defect is located on the long arm of chromosome 12, where the PAH gene encodes the protein, phenylalanine hydroxylase.

Bentall Procedure: Indications, Surgical Steps, Risks, Recovery, and Long-Term Outcomes

Bentall Procedure: Indications, Surgical Steps, Risks, Recovery, and Long-Term Outcomes

pediagenosis    August 07, 2026   

Bentall Procedure

Keywords: Bentall Procedure, Operations for Valvular Heart Disease, bentall, aortic replacement, valve replacement, composite aortic valve, aortic replacement.

Abstract

The Bentall procedure technique has evolved to become a standardized, reliable procedure that can be performed for a variety of aortic vavle and aortic root pathology. The technique described in this chapter describes the details of the author’s technique and variations for specific pathology. Myocardial protection and cerebral protection is discussed.

Male Pseudohermaphroditism (46,XY DSD): Causes, Symptoms, Diagnosis, Treatment & Gonadal Disorders

Male Pseudohermaphroditism (46,XY DSD): Causes, Symptoms, Diagnosis, Treatment & Gonadal Disorders

pediagenosis    August 07, 2026   

INTERSEX: MALE PSEUDOHERMAPHRODITISM I GONADAL

The pseudohermaphrodite is an individual with the gonads of only one sex but with genitalia (internal and external) and secondary sex characters exhibiting sexual ambiguity. Such a simple classification of intersex is based purely on phenotype or morphology, without regard to genetic etiology. Factors that contribute to such disordered development include (1) gene mutations, (2) abnormal maternal hormonal influences, and (3) abnormal hormonal influences from the embryonic gonad, adrenal, or other endocrine organ. The type and degree of disordered development depend on the intensity and timing of these influences during embryonic life.

Scrotal Wall Anatomy: Layers, Structure, Functions, Embryology & Clinical Significance

Scrotal Wall Anatomy: Layers, Structure, Functions, Embryology & Clinical Significance

pediagenosis    August 07, 2026   

SCROTAL WALL

The testicles are maintained in position within the scrotal cavity by the structures of the spermatic cord. Each testicle and spermatic cord is invested in six distinct tissue layers that are acquired as a result of the descent of the gonads from the retroperitoneum into the scrotum during fetal life.

Tracheal Resection and Anastomosis: Surgical Procedure, Indications, Techniques, Risks, and Recovery

Tracheal Resection and Anastomosis: Surgical Procedure, Indications, Techniques, Risks, and Recovery

pediagenosis    August 02, 2026    Comment   

TRACHEAL RESECTION AND ANASTOMOSIS

Tracheal stenosis can be idiopathic but is most commonly the result of prior intubation or tracheostomy. Common areas of stenosis were previously located in the mid-trachea related to high-pressure, low-volume endotracheal tube cuffs; however, contemporary endotracheal appliances have low-pressure cuffs. Today stenotic lesions are typically found in the proximal or subglottic trachea at the site of a prior stoma. Mid- to distal tracheal resections are more likely performed as therapy for benign or malignant airway tumors. In most cases of symptom-producing stenosis of the trachea, conservative therapy, consisting of repeated dilatations, is either contraindicated or has proven to be ineffective. Consequently, surgical correction is necessary. The procedure of choice is resection of the stenotic tracheal segment with primary reconstruction via an end-to-end anastomosis (see illustration).

Removal of Mediastinal Tumors: Surgical Approaches, Mediastinal Anatomy, Diagnosis, and Treatment Guide

Removal of Mediastinal Tumors: Surgical Approaches, Mediastinal Anatomy, Diagnosis, and Treatment Guide

pediagenosis    August 02, 2026    Comment   

REMOVAL OF MEDIASTINAL TUMORS

Tumors of the mediastinum are a challenging group both diagnostically and in terms of treatment. A host of pathologic entities is involved, and for many of these, surgical excision is the treatment of choice. Recognition and identification of mediastinal abnormalities are almost always based on chest radiographs. Although the radiologic appearance is sometimes characteristic or (rarely) pathognomonic, most often it is the location within the mediastinum that is most influential in correct diagnostic interpretation.

Congenital Radioulnar Synostosis: Causes, Symptoms, Diagnosis, Treatment & Functional Outcomes

Congenital Radioulnar Synostosis: Causes, Symptoms, Diagnosis, Treatment & Functional Outcomes

pediagenosis    July 31, 2026    Comment   

CONGENITAL RADIOULNAR SYNOSTOSIS

Congenital radioulnar synostosis is an uncommon condition in which the proximal ends of the radius and ulna are joined, fixing the forearm in pronation. The deformity is due to a failure of the developing cartilaginous precursors of the forearm to separate during fetal development. Radioulnar synostosis is bilateral in 60% of patients and is frequently associated with other musculoskeletal abnormalities. Chromosomal abnormalities have been reported in some patients with bilateral involvement. Two types of synostosis are seen. In the first, called the headless type, the medullary canals of the radius and ulna are joined and the proximal radius is absent or malformed and fused to the ulna over a distance of several centimeters. The radius is anteriorly bowed and its diaphysis is larger and longer than that of the ulna. In the second type, the fused segment is shorter and the radius is formed normally but the radial head is dislocated anteriorly or posteriorly and fused to the diaphysis of the proximal ulna. The second type is often unilateral and sometimes associated with deformities such as syndactyly or supernumerary thumbs.

Scurvy (Vitamin C Deficiency): Symptoms, Causes, Diagnosis, Treatment, and Prevention

Scurvy (Vitamin C Deficiency): Symptoms, Causes, Diagnosis, Treatment, and Prevention

pediagenosis    July 31, 2026    Comment   

DIETARY SOURCES OF VITAMIN C AND CLASSIC CUTANEOUS MANIFESTATIONS OF SCURVY

SCURVY

Scurvy is a well-known nutritional disease that results from a lack of the water-soluble vitamin, ascorbic acid (vitamin C). Scurvy has a well-documented history. It was first recognized in the fourteenth century in sailors who spent long amounts of time at sea. The symptoms were recognized as being related to a lack of fresh foods, especially citrus products. In 1753, James Lind, a British surgeon aboard the HMS Salisbury, performed the first documented clinical trial proving that scurvy was caused by a lack of citrus fruit in the diet of sailors. After Lind’s discovery, citrus fruits were included in ships’ provisions, and the incidence of scurvy in sailors plummeted. It was not until 1928 that ascorbic acid was isolated by the Hungarian chemist, Albert von Szent-Grörgyi, who was eventually awarded the Nobel Prize for this discovery. Scurvy is still present in some areas of the world due to inadequate dietary intake of vitamin C. Scurvy is uncommon in North America but can be seen in individuals with abnormal diets.

Sublobar Resection and Surgical Lung Biopsy: Segmentectomy vs Wedge Resection Explained

Sublobar Resection and Surgical Lung Biopsy: Segmentectomy vs Wedge Resection Explained

pediagenosis    July 30, 2026    Comment   

SUBLOBAR RESECTION AND SURGICAL LUNG BIOPSY

Segmental Resection

Resection of lung tissue anatomically less than a lobe is carried out for localized lesions such as benign tumors, granulomas, tuberculous foci, bronchiectasis, metastatic cancers, and others and to obtain tissue specimens required for the diagnosis of diffuse pulmonary disease processes. Recent evidence suggests anatomic segmentectomy may provide survival equivalent to lobectomy for small (2 cm) primary lung cancers in the absence of regional node involvement.

Lobectomy Surgery: Procedure, Indications, Surgical Technique, Risks, Recovery, and Postoperative Care

Lobectomy Surgery: Procedure, Indications, Surgical Technique, Risks, Recovery, and Postoperative Care

pediagenosis    July 30, 2026    Comment   

LOBECTOMY

Lobectomy is a more difficult procedure to perform than pneumonectomy, particularly in the presence of chronic inflammatory changes or where tumor (or involved lymph nodes) involves the lobar hilum. Not only must the critical lobar structures be individually identified and controlled by the surgeon, but the remaining structures must be painstakingly protected and preserved. Incomplete fissures may add to the problem, and the surgeon must possess a precise knowledge of hilar anatomy and common anomalies.